@article{ISI:000340579900011, author = {Stefanak, Martin and Bezdekova, Iva and Jex, Igor and Barnett, Stephen M.}, title = {{STABILITY OF POINT SPECTRUM FOR THREE-STATE QUANTUM WALKS ON A LINE}}, journal = {{QUANTUM INFORMATION \& COMPUTATION}}, year = {{2014}}, volume = {{14}}, number = {{13-14}}, pages = {{1213-1226}}, month = {{OCT}}, abstract = {{Evolution operators of certain quantum walks possess, apart from the continuous part, also a point spectrum. The existence of eigenvalues and the corresponding stationary states lead to partial trapping of the walker in the vicinity of the origin. We analyze the stability of this feature for three-state quantum walks on a line subject to homogenous coin deformations. We find two classes of coin operators that preserve the point spectrum. These new classes of coins are generalizations of coins found previously by different methods and shed light on the rich spectrum of coins that can drive discrete-time quantum walks.}}, publisher = {{RINTON PRESS, INC}}, address = {{565 EDMUND TERRACE, PARAMUS, NJ 07652 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Brehova, Czech Republic. Stefanak, Martin; Bezdekova, Iva; Jex, Igor, Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Brehova, Czech Republic. Barnett, Stephen M., Univ Glasgow, Sch Phys \& Astron, Glasgow G12 8QQ, Lanark, Scotland.}}, issn = {{1533-7146}}, keywords = {{quantum walk; localization}}, keywords-plus = {{LOCALIZATION}}, research-areas = {{Computer Science; Physics}}, web-of-science-categories = {{Computer Science, Theory \& Methods; Physics, Particles \& Fields; Physics, Mathematical}}, researcherid-numbers = {{Stefanak, Martin/G-5239-2012}}, funding-acknowledgement = {{RVO {[}68407700, SGS13/217/OHK4/3T/14]; GAR {[}13-33906S]; GACR {[}14-02901P]}}, funding-text = {{The financial support from RVO 68407700, SGS13/217/OHK4/3T/14, GAR 13-33906S and GACR 14-02901P is gratefully acknowledged.}}, number-of-cited-references = {{25}}, times-cited = {{1}}, journal-iso = {{Quantum Inform. Comput.}}, doc-delivery-number = {{AN4SX}}, unique-id = {{ISI:000340579900011}} }
@article{ISI:000341115200006, author = {Hamilton, Craig S. and Kruse, Regina and Sansoni, Linda and Silberhorn, Christine and Jex, Igor}, title = {{Driven Quantum Walks}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{2014}}, volume = {{113}}, number = {{8}}, month = {{AUG 21}}, abstract = {{We introduce the concept of a driven quantum walk. This work is motivated by recent theoretical and experimental progress that combines quantum walks and parametric down-conversion, leading to fundamentally different phenomena. We compare these striking differences by relating the driven quantum walks to the original quantum walk. Next, we illustrate typical dynamics of such systems and show that these walks can be controlled by various pump configurations and phase matchings. Finally, we end by proposing an application of this process based on a quantum search algorithm that performs faster than a classical search.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Hamilton, CS (Reprint Author), Czech Tech Univ, FNSPE, Brehova 7, Prague 11519 1, Czech Republic. Hamilton, Craig S.; Jex, Igor, Czech Tech Univ, FNSPE, Prague 11519 1, Czech Republic. Kruse, Regina; Sansoni, Linda; Silberhorn, Christine, Univ Paderborn, D-33098 Paderborn, Germany.}}, doi = {{10.1103/PhysRevLett.113.083602}}, article-number = {{083602}}, issn = {{0031-9007}}, eissn = {{1079-7114}}, keywords-plus = {{SIMULATION; TREES}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{hamilcra@fjfi.cvut.cz}}, funding-acknowledgement = {{ {[}RVO 68407700]; {[}GACR 13-33906 S]}}, funding-text = {{C. S. H. and I. J. received financial support from Grants No. RVO 68407700 and No. GACR 13-33906 S.}}, number-of-cited-references = {{32}}, times-cited = {{0}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{AO1ZV}}, unique-id = {{ISI:000341115200006}} }
@article{ISI:000341232500003, author = {Stefanak, M. and Bezdekova, I. and Jex, I.}, title = {{Limit distributions of three-state quantum walks: The role of coin eigenstates}}, journal = {{PHYSICAL REVIEW A}}, year = {{2014}}, volume = {{90}}, number = {{1}}, month = {{JUL 31}}, abstract = {{We analyze two families of three-state quantum walks which show the localization effect. We focus on the role of the initial coin state and its coherence in controlling the properties of the quantum walk. In particular, we show that the description of the walk simplifies considerably when the initial coin state is decomposed in the basis formed by the eigenvectors of the coin operator. This allows us to express the limit distributions in a much more convenient form. Consequently, striking features which are hidden in the standard basis description are easily identified. Moreover, the dependence of moments of the position distribution on the initial coin state can be analyzed in full detail. In particular, we find that in the eigenvector basis the even moments and the localization probability at the origin depend only on incoherent combination of probabilities. In contrast, odd moments and localization outside the origin are affected by the coherence of the initial coin state.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague 1, Stare Mesto, Czech Republic. Stefanak, M.; Bezdekova, I.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Stare Mesto, Czech Republic.}}, doi = {{10.1103/PhysRevA.90.012342}}, article-number = {{012342}}, issn = {{1050-2947}}, eissn = {{1094-1622}}, keywords-plus = {{ONE-DIMENSION; LOCALIZATION}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{martin.stefanak@fjfi.cvut.cz}}, researcherid-numbers = {{Stefanak, Martin/G-5239-2012}}, funding-acknowledgement = {{{[}RVO 68407700]; {[}GACR 14-02901P]; {[}SGS13/217/OHK4/3T/14]; {[}GACR 13-33906S]}}, funding-text = {{We appreciate the financial support from Grant No. RVO 68407700. M.S.. is grateful for Grant No. GACR 14-02901P. I.B. and I.J. are thankful for the financial support from Grants No. SGS13/217/OHK4/3T/14 and No. GACR 13-33906S.}}, number-of-cited-references = {{38}}, times-cited = {{0}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{AO3LY}}, unique-id = {{ISI:000341232500003}} }
@article{ISI:000336809800001, author = {Kollar, Balint and Novotny, Jaroslav and Kiss, Tamas and Jex, Igor}, title = {{Discrete time quantum walks on percolation graphs}}, journal = {{EUROPEAN PHYSICAL JOURNAL PLUS}}, year = {{2014}}, volume = {{129}}, number = {{5}}, month = {{MAY 30}}, abstract = {{Randomly breaking connections in a graph alters its transport properties, a model used to describe percolation. In the case of quantum walks, dynamic percolation graphs represent a special type of imperfections, where the connections appear and disappear randomly in each step during the time evolution. The resulting open system dynamics is hard to treat numerically in general. We shortly review the literature on this problem. We then present our method to solve the evolution on finite percolation graphs in the long time limit, applying the asymptotic methods concerning random unitary maps. We work out the case of one-dimensional chains in detail and provide a concrete, step-by-step numerical example in order to give more insight into the possible asymptotic behavior. The results about the case of the two-dimensional integer lattice are summarized, focusing on the Grover-type coin operator.}}, publisher = {{SPRINGER HEIDELBERG}}, address = {{TIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY}}, type = {{Article}}, language = {{English}}, affiliation = {{Kollar, B (Reprint Author), SZFKI, Wigner RCP, Konkoly Thege M U 29-33, H-1121 Budapest, Hungary. Kollar, Balint; Kiss, Tamas, SZFKI, Wigner RCP, H-1121 Budapest, Hungary. Novotny, Jaroslav; Jex, Igor, Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Stare Mesto, Czech Republic.}}, doi = {{10.1140/epjp/i2014-14103-6}}, article-number = {{103}}, issn = {{2190-5444}}, keywords-plus = {{DECOHERENCE; DYNAMICS; PHOTONS}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{kollar.balint@wigner.mta.hu}}, funding-acknowledgement = {{Hungarian Scientific Research Fund (OTKA) {[}K83858, NN109651]; Hungarian Academy of Sciences (Lendulet Program) {[}LP2011-016]; {[}GACR 13-33906S]; {[}RVO 68407700]}}, funding-text = {{We acknowledge support by GACR 13-33906S, RVO 68407700, the Hungarian Scientific Research Fund (OTKA) under Contract Nos. K83858, NN109651, the Hungarian Academy of Sciences (Lendulet Program, LP2011-016).}}, number-of-cited-references = {{65}}, times-cited = {{0}}, journal-iso = {{Eur. Phys. J. Plus}}, doc-delivery-number = {{AI4BG}}, unique-id = {{ISI:000336809800001}} }
@article{ISI:000332612000002, author = {Kollar, B. and Novotny, J. and Kiss, T. and Jex, I.}, title = {{Percolation induced effects in two-dimensional coined quantum walks: analytic asymptotic solutions}}, journal = {{NEW JOURNAL OF PHYSICS}}, year = {{2014}}, volume = {{16}}, month = {{FEB 4}}, abstract = {{Quantum walks on graphs can model physical processes and serve as efficient tools in quantum information theory. Once we admit random variations in the connectivity of the underlying graph, we arrive at the problem of percolation, where the long-time behaviour appears untreatable with direct numerical methods. We develop novel analytic methods based on the theory of random unitary operations which help us to determine explicitly the asymptotic dynamics of quantum walks on two-dimensional finite integer lattices with percolation. Based on this theory, we find new unexpected features of percolated walks like asymptotic position inhomogeneity or special directional symmetry breaking.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Kollar, B (Reprint Author), SZFKI, Wigner RCP, Konkoly Thege Miklos Ut 29-33, H-1121 Budapest, Hungary. Kollar, B.; Kiss, T., SZFKI, Wigner RCP, H-1121 Budapest, Hungary. Kollar, B., Univ Pecs, Inst Phys, H-7624 Pecs, Hungary. Novotny, J.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Stare Mesto, Czech Republic.}}, doi = {{10.1088/1367-2630/16/2/023002}}, article-number = {{23002}}, issn = {{1367-2630}}, keywords-plus = {{DECOHERENCE; DYNAMICS; PHOTONS}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{kollar.balint@wigner.mta.hu}}, researcherid-numbers = {{Kollar, Balint/J-2297-2012 Kiss, Tamas/B-9228-2009}}, funding-acknowledgement = {{MSM {[}6840770039]; GACR {[}13-33906S]; RVO {[}68407700]; Hungarian Scientific Research Fund (OTKA) {[}K83858, NN109651]; Hungarian Academy of Sciences (Lendulet Program) {[}LP2011-016]; European Union; State of Hungary; European Social Fund {[}TAMOP 4.2.4.A/2-11-1-2012-0001]}}, funding-text = {{We acknowledge support by MSM 6840770039, GACR 13-33906S, RVO 68407700, the Hungarian Scientific Research Fund (OTKA) under contract numbers K83858, NN109651, the Hungarian Academy of Sciences (Lendulet Program, LP2011-016). BK acknowledges support by the European Union and the State of Hungary, co-financed by the European Social Fund in the framework of TAMOP 4.2.4.A/2-11-1-2012-0001 `National Excellence Program'.}}, number-of-cited-references = {{48}}, times-cited = {{1}}, journal-iso = {{New J. Phys.}}, doc-delivery-number = {{AC6DQ}}, unique-id = {{ISI:000332612000002}} }
@article{ISI:000323480500001, author = {Kruse, R. and Katzschmann, F. and Christ, A. and Schreiber, A. and Wilhelm, S. and Laiho, K. and Gabris, A. and Hamilton, C. S. and Jex, I. and Silberhorn, C.}, title = {{Spatio-spectral characteristics of parametric down-conversion in waveguide arrays}}, journal = {{NEW JOURNAL OF PHYSICS}}, year = {{2013}}, volume = {{15}}, month = {{AUG 23}}, abstract = {{High dimensional quantum states are of fundamental interest for quantum information processing. They give access to large Hilbert spaces and, in turn, enable the encoding of quantum information on multiple modes. One method to create such quantum states is parametric down-conversion (PDC) in waveguide arrays (WGAs) which allows for the creation of highly entangled photon pairs in controlled, easily accessible spatial modes, with unique spectral properties. In this paper we examine both theoretically and experimentally the PDC process in a lithium niobate WGA. We measure the spatial and spectral properties of the emitted photon pairs, revealing correlations between spectral and spatial degrees of freedom of the created photons. Our measurements show that, in contrast to prior theoretical approaches, spectrally dependent coupling effects have to be taken into account in the theory of PDC in WGAs. To interpret the results, we developed a theoretical model specifically taking into account spectrally dependent coupling effects, which further enables us to explore the capabilities and limitations for engineering the spatial correlations of the generated quantum states.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Kruse, R (Reprint Author), Univ Paderborn, Warburger Str 100, D-33098 Paderborn, Germany. Kruse, R.; Katzschmann, F.; Christ, A.; Schreiber, A.; Wilhelm, S.; Laiho, K.; Silberhorn, C., Univ Paderborn, D-33098 Paderborn, Germany. Schreiber, A.; Silberhorn, C., Max Planck Inst Sci Light, D-91058 Erlangen, Germany. Laiho, K., Univ Innsbruck, Inst Expt Phys Photon, A-6020 Innsbruck, Austria. Gabris, A.; Hamilton, C. S.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic. Gabris, A., Hungarian Acad Sci, Wigner Res Ctr Phys, H-1525 Budapest, Hungary.}}, doi = {{10.1088/1367-2630/15/8/083046}}, article-number = {{083046}}, issn = {{1367-2630}}, keywords-plus = {{ENTANGLED PHOTON PAIRS; LITHIUM-NIOBATE; DIRECTIONAL-COUPLERS; INTERFERENCE; INFORMATION; GENERATION; SOLITONS; OPTICS; PUMP}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{rkruse2@mail.upb.de}}, funding-acknowledgement = {{MSM {[}6840770039]; RVO {[}68407700]; GACR {[}13-33906S]; National Research Fund of Hungary {[}T83858]}}, funding-text = {{The authors thank Harald Herrmann and Hubertus Suche for useful discussions and helpful comments. The authors further thank Frank Setzpfandt and Thomas Pertsch for discussions concerning the experimental setup. AG, CSH and IJ received funding from MSM 6840770039, RVO 68407700 and GACR 13-33906S. AG acknowledges partial support from the National Research Fund of Hungary under contract no. T83858.}}, number-of-cited-references = {{48}}, times-cited = {{4}}, journal-iso = {{New J. Phys.}}, doc-delivery-number = {{205YI}}, unique-id = {{ISI:000323480500001}} }
@article{ISI:000322605800016, author = {Rohde, Peter P. and Schreiber, Andreas and Stefanak, Martin and Jex, Igor and Gilchrist, Alexei and Silberhorn, Christine}, title = {{Increasing the Dimensionality of Quantum Walks Using Multiple Walkers}}, journal = {{JOURNAL OF COMPUTATIONAL AND THEORETICAL NANOSCIENCE}}, year = {{2013}}, volume = {{10}}, number = {{7, SI}}, pages = {{1644-1652}}, month = {{JUL}}, abstract = {{We show that with the addition of multiple walkers, quantum walks on a line can be transformed into lattice graphs of higher dimension. Thus, multi-walker walks can simulate single-walker walks on higher dimensional graphs and vice versa. This exponential complexity opens up new applications for present-day quantum walk experiments. We discuss the applications of such higher-dimensional structures and how they relate to linear optics quantum computing. In particular we show that multi-walker quantum walks are equivalent to the BOSONSAMPLING model for linear optics quantum computation proposed by Aaronson and Arkhipov. With the addition of control over phase-defects in the lattice, which can be simulated with entangling gates, asymmetric lattice structures can be constructed which are universal for quantum computation.}}, publisher = {{AMER SCIENTIFIC PUBLISHERS}}, address = {{26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Rohde, PP (Reprint Author), Univ Paderborn, Warburger Str 100, D-33098 Paderborn, Germany. Rohde, Peter P.; Schreiber, Andreas; Silberhorn, Christine, Univ Paderborn, D-33098 Paderborn, Germany. Rohde, Peter P.; Gilchrist, Alexei, Macquarie Univ, Dept Phys \& Astron, Ctr Engn Quantum Syst, Sydney, NSW 2113, Australia. Schreiber, Andreas; Silberhorn, Christine, Max Planck Inst Sci Light, D-91058 Erlangen, Germany. Stefanak, Martin; Jex, Igor, Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic.}}, doi = {{10.1166/jctn.2013.3104}}, issn = {{1546-1955}}, keywords = {{Quantum; Walk; Complexity}}, keywords-plus = {{COMPUTATION}}, research-areas = {{Chemistry; Science \& Technology - Other Topics; Materials Science; Physics}}, web-of-science-categories = {{Chemistry, Multidisciplinary; Nanoscience \& Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter}}, researcherid-numbers = {{Stefanak, Martin/G-5239-2012 Silberhorn, Christine/J-4919-2013 Gilchrist, Alexei/B-9968-2009}}, orcid-numbers = {{Silberhorn, Christine/0000-0002-2349-5443 }}, funding-acknowledgement = {{Australian Research Council Centre of Excellence for Engineered Quantum Systems {[}CE110001013]; Czech Ministry of Education {[}MSM 6840770039]; Doppler Institute, FNSPE CTU in Prague}}, funding-text = {{We thank Timothy Ralph, Scott Aaronson and Aurel Gabris for helpful discussions. This research was conducted by the Australian Research Council Centre of Excellence for Engineered Quantum Systems (Project number CE110001013). We acknowledge support by the grant MSM 6840770039 of the Czech Ministry of Education and the Doppler Institute, FNSPE CTU in Prague.}}, number-of-cited-references = {{30}}, times-cited = {{1}}, journal-iso = {{J. Comput. Theor. Nanosci.}}, doc-delivery-number = {{194BK}}, unique-id = {{ISI:000322605800016}} }
@article{ISI:000311337400011, author = {Novotny, J. and Alber, G. and Jex, I.}, title = {{Asymptotic properties of quantum Markov chains}}, journal = {{JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL}}, year = {{2012}}, volume = {{45}}, number = {{48}}, month = {{DEC 7}}, abstract = {{The asymptotic dynamics of discrete quantum Markov chains generated by the most general physically relevant quantum operations is investigated. It is shown that it is confined to an attractor space in which the resulting quantum Markov chain is diagonalizable. A construction procedure of a basis of this attractor space and its associated dual basis of 1-forms is presented. It is applicable whenever a strictly positive quantum state exists which is contracted or left invariant by the generating quantum operation. Moreover, algebraic relations between the attractor space and Kraus operators involved in the definition of a quantum Markov chain are derived. This construction is not only expected to offer significant computational advantages in cases in which the dimension of the Hilbert space is large and the dimension of the attractor space is small, but it also sheds new light onto the relation between the asymptotic dynamics of discrete quantum Markov chains and fixed points of their generating quantum operations. Finally, we show that without any restriction our construction applies to all initial states whose support belongs to the so-called recurrent subspace.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Czech Tech Univ, Dept Phys, FNSPE, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Novotny, J.; Jex, I., Czech Tech Univ, Dept Phys, FNSPE, Prague 11519 1, Stare Mesto, Czech Republic. Alber, G., Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany.}}, doi = {{10.1088/1751-8113/45/48/485301}}, article-number = {{485301}}, issn = {{1751-8113}}, eissn = {{1751-8121}}, keywords-plus = {{FIXED-POINTS; OPERATIONS; MAPS}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary; Physics, Mathematical}}, author-email = {{novotny.jaroslav@seznam.cz}}, funding-acknowledgement = {{Czech Ministry of Education {[}MSM 6840770039]; Doppler Institute, FNSPE CTU in Prague; CASED AB1}}, funding-text = {{JN and IJ acknowledge support by the grant MSM 6840770039 of the Czech Ministry of Education and the Doppler Institute, FNSPE CTU in Prague, GA acknowledges support by CASED AB1.}}, number-of-cited-references = {{27}}, times-cited = {{2}}, journal-iso = {{J. Phys. A-Math. Theor.}}, doc-delivery-number = {{040QH}}, unique-id = {{ISI:000311337400011}} }
@article{ISI:000305526600004, author = {Nikolopoulos, G. M. and Hoskovec, A. and Jex, I.}, title = {{Analysis and minimization of bending losses in discrete quantum networks}}, journal = {{PHYSICAL REVIEW A}}, year = {{2012}}, volume = {{85}}, number = {{6}}, month = {{JUN 21}}, abstract = {{We study theoretically the transfer of quantum information along bends in two-dimensional discrete lattices. Our analysis shows that the fidelity of the transfer decreases considerably as a result of interactions in the neighborhood of the bend. It is also demonstrated that such losses can be controlled efficiently by the inclusion of a defect. The present results are of relevance to various physical implementations of quantum networks, where geometric imperfections with finite spatial extent may arise as a result of bending, residual stress, etc.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Nikolopoulos, GM (Reprint Author), FORTH, Inst Elect Struct \& Laser, POB 1527, GR-71110 Iraklion, Greece. Nikolopoulos, G. M., FORTH, Inst Elect Struct \& Laser, GR-71110 Iraklion, Greece. Hoskovec, A.; Jex, I., Czech Tech Univ, Dept Phys, FNSPE, Prague 11519 1, Stare Mesto, Czech Republic.}}, doi = {{10.1103/PhysRevA.85.062319}}, article-number = {{062319}}, issn = {{1050-2947}}, keywords-plus = {{ELECTRON WAVEPACKET PROPAGATION; STATE TRANSFER; DOTS; ENTANGLEMENT; DYNAMICS; PERFECT; SYSTEMS; CHAIN}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Nikolopoulos, Georgios/H-3023-2011}}, orcid-numbers = {{Nikolopoulos, Georgios/0000-0002-3937-2771}}, funding-acknowledgement = {{Czech Ministry of Education {[}3132MSM6840770039]; Czech Technical University in Prague {[}SGS10/294/OHK4/3T/14]; DI FNSPE CTU in Prague}}, funding-text = {{We acknowledge support from Grants No. 3132MSM6840770039 of the Czech Ministry of Education, No. SGS10/294/OHK4/3T/14 of the Czech Technical University in Prague, and the DI FNSPE CTU in Prague.}}, number-of-cited-references = {{34}}, times-cited = {{2}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{962FK}}, unique-id = {{ISI:000305526600004}} }
@article{ISI:000304806100003, author = {Kollar, B. and Kiss, T. and Novotny, J. and Jex, I.}, title = {{Asymptotic Dynamics of Coined Quantum Walks on Percolation Graphs}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{2012}}, volume = {{108}}, number = {{23}}, month = {{JUN 5}}, abstract = {{Quantum walks obey unitary dynamics: they form closed quantum systems. The system becomes open if the walk suffers from imperfections represented as missing links on the underlying basic graph structure, described by dynamical percolation. Openness of the system's dynamics creates decoherence, leading to strong mixing. We present a method to analytically solve the asymptotic dynamics of coined, percolated quantum walks for a general graph structure. For the case of a circle and a linear graph we derive the explicit form of the asymptotic states. We find that a rich variety of asymptotic evolutions occur: not only the fully mixed state, but other stationary states; stable periodic and quasiperiodic oscillations can emerge, depending on the coin operator, the initial state, and the topology of the underlying graph.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Kollar, B (Reprint Author), SZFKI, WIGNER RCP, Konkoly Thege Miklos Ut 29-33, H-1121 Budapest, Hungary. Kollar, B.; Kiss, T., SZFKI, WIGNER RCP, H-1121 Budapest, Hungary. Novotny, J.; Jex, I., Czech Tech Univ, Dept Phys, Fac Nucl Sci \& Phys Engn, Prague 11519 1, Stare Mesto, Czech Republic.}}, doi = {{10.1103/PhysRevLett.108.230505}}, article-number = {{230505}}, issn = {{0031-9007}}, keywords-plus = {{DECOHERENCE}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Kollar, Balint/J-2297-2012}}, funding-acknowledgement = {{MSM {[}6840770039]; DI FNSPE CTU in Prague; Hungarian Scientific Research Fund (OTKA) {[}K83858]; Hungarian Academy of Sciences {[}LP2011-016]}}, funding-text = {{We acknowledge support by MSM 6840770039, DI FNSPE CTU in Prague, the Hungarian Scientific Research Fund (OTKA) under Contract No. K83858, and the Hungarian Academy of Sciences (Lendulet Program, LP2011-016).}}, number-of-cited-references = {{31}}, times-cited = {{9}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{952QB}}, unique-id = {{ISI:000304806100003}} }
@article{ISI:000305245400032, author = {Stefanak, M. and Bezdekova, I. and Jex, I.}, title = {{Continuous deformations of the Grover walk preserving localization}}, journal = {{EUROPEAN PHYSICAL JOURNAL D}}, year = {{2012}}, volume = {{66}}, number = {{5}}, month = {{MAY}}, abstract = {{The three-state Grover walk on a line exhibits the localization effect characterized by a non-vanishing probability of the particle to stay at the origin. We present two continuous deformations of the Grover walk which preserve its localization nature. The resulting quantum walks differ in the rate at which they spread through the lattice. The velocities of the left and right-traveling probability peaks are given by the maximum of the group velocity. We find the explicit form of peak velocities in dependence on the coin parameter. Our results show that localization of the quantum walk is not a singular property of an isolated coin operator but can be found for entire families of coins.}}, publisher = {{SPRINGER}}, address = {{233 SPRING ST, NEW YORK, NY 10013 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague 1, Stare Mesto, Czech Republic. Stefanak, M.; Bezdekova, I.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Stare Mesto, Czech Republic.}}, doi = {{10.1140/epjd/e2012-30146-9}}, article-number = {{142}}, issn = {{1434-6060}}, keywords-plus = {{QUANTUM RANDOM-WALKS; LIMIT-THEOREMS; ONE-DIMENSION}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{martin.stefanak@fjfi.cvut.cz}}, researcherid-numbers = {{Stefanak, Martin/G-5239-2012}}, funding-acknowledgement = {{ {[}MSM 6840770039]; {[}MSMT LC06002]; {[}SGS11/132/OHK4/2T/14]}}, funding-text = {{We acknowledge the financial support from MSM 6840770039, MSMT LC06002 and SGS11/132/OHK4/2T/14.}}, number-of-cited-references = {{27}}, times-cited = {{2}}, journal-iso = {{Eur. Phys. J. D}}, doc-delivery-number = {{958NJ}}, unique-id = {{ISI:000305245400032}} }
@article{ISI:000302405400048, author = {Schreiber, Andreas and Gabris, Aurel and Rohde, Peter P. and Laiho, Kaisa and Stefanak, Martin and Potocek, Vaclav and Hamilton, Craig and Jex, Igor and Silberhorn, Christine}, title = {{A 2D Quantum Walk Simulation of Two-Particle Dynamics}}, journal = {{SCIENCE}}, year = {{2012}}, volume = {{336}}, number = {{6077}}, pages = {{55-58}}, month = {{APR 6}}, abstract = {{Multidimensional quantum walks can exhibit highly nontrivial topological structure, providing a powerful tool for simulating quantum information and transport systems. We present a flexible implementation of a two-dimensional (2D) optical quantum walk on a lattice, demonstrating a scalable quantum walk on a nontrivial graph structure. We realized a coherent quantum walk over 12 steps and 169 positions by using an optical fiber network. With our broad spectrum of quantum coins, we were able to simulate the creation of entanglement in bipartite systems with conditioned interactions. Introducing dynamic control allowed for the investigation of effects such as strong nonlinearities or two-particle scattering. Our results illustrate the potential of quantum walks as a route for simulating and understanding complex quantum systems.}}, publisher = {{AMER ASSOC ADVANCEMENT SCIENCE}}, address = {{1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Schreiber, A (Reprint Author), Univ Paderborn, Warburger Str 100, D-33098 Paderborn, Germany. Schreiber, Andreas; Rohde, Peter P.; Laiho, Kaisa; Silberhorn, Christine, Univ Paderborn, D-33098 Paderborn, Germany. Schreiber, Andreas; Laiho, Kaisa; Silberhorn, Christine, Max Planck Inst Sci Light, D-91058 Erlangen, Germany. Gabris, Aurel; Stefanak, Martin; Potocek, Vaclav; Hamilton, Craig; Jex, Igor, Czech Tech Univ, Dept Phys, Fac Nucl Sci \& Phys Engn, Prague 11519, Czech Republic. Gabris, Aurel, Hungarian Acad Sci, Wigner Res Ctr Phys, H-1525 Budapest, Hungary. Rohde, Peter P., Macquarie Univ, Ctr Engn Quantum Syst, Dept Phys \& Astron, Sydney, NSW 2113, Australia.}}, doi = {{10.1126/science.1218448}}, issn = {{0036-8075}}, research-areas = {{Science \& Technology - Other Topics}}, web-of-science-categories = {{Multidisciplinary Sciences}}, author-email = {{andreas.schreiber@uni-paderborn.de}}, researcherid-numbers = {{Stefanak, Martin/G-5239-2012 Silberhorn, Christine/J-4919-2013}}, orcid-numbers = {{Silberhorn, Christine/0000-0002-2349-5443}}, funding-acknowledgement = {{German Israel Foundation {[}970/2007]; Australian Research Council Centre of Excellence for Engineered Quantum Systems {[}CE110001013]; {[}MSM6840770039]; {[}MSMT LC06002]; {[}SGS10/294/OHK4/3T/14]; {[}GA CR 202/08/H078]; {[}OTKA T83858]}}, funding-text = {{We acknowledge financial support from the German Israel Foundation (project no. 970/2007). A.G., M.S., V.P., C.H., and I.J. acknowledge grant support from MSM6840770039 and MSMT LC06002, SGS10/294/OHK4/3T/14, GA CR 202/08/H078, and OTKA T83858. P.P.R. acknowledges support from the Australian Research Council Centre of Excellence for Engineered Quantum Systems (project no. CE110001013).}}, number-of-cited-references = {{27}}, times-cited = {{63}}, journal-iso = {{Science}}, doc-delivery-number = {{920LG}}, unique-id = {{ISI:000302405400048}} }
@inproceedings{ISI:000310362402233, author = {Schreiber, A. and Gabris, A. and Rohde, P. P. and Laiho, K. and Stefanak, M. and Potocek, V. and Hamilton, C. and Jex, I. and Silberhorn, C.}, book-group-author = {{IEEE}}, title = {{Quantum simulations with a two-dimensional Quantum Walk}}, booktitle = {{2012 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)}}, year = {{2012}}, note = {{Conference on Lasers and Electro-Optics (CLEO), San Jose, CA, MAY 06-11, 2012}}, abstract = {{We present an experimental implementation of a quantum walk in two dimensions, employing an optical fiber network. We simulated entangling operations and nonlinear multi-particle interactions revealing phenomena such as bound states. (C) 2011 Optical Society of America}}, publisher = {{IEEE}}, address = {{345 E 47TH ST, NEW YORK, NY 10017 USA}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{Schreiber, A (Reprint Author), Max Planck Inst Sci Light, Gunther Scharowsky Str 1 Bau 26, D-91058 Erlangen, Germany. Schreiber, A.; Laiho, K.; Silberhorn, C., Max Planck Inst Sci Light, D-91058 Erlangen, Germany.}}, isbn = {{978-1-55752-933-6}}, research-areas = {{Engineering; Optics; Physics}}, web-of-science-categories = {{Engineering, Electrical \& Electronic; Optics; Physics, Applied}}, author-email = {{Andreas.Schreiber@mpl.mpg.de}}, researcherid-numbers = {{Stefanak, Martin/G-5239-2012 Silberhorn, Christine/J-4919-2013}}, orcid-numbers = {{Silberhorn, Christine/0000-0002-2349-5443}}, number-of-cited-references = {{4}}, times-cited = {{0}}, doc-delivery-number = {{BCK05}}, unique-id = {{ISI:000310362402233}} }
@article{ISI:000295005900017, author = {Brougham, T. and Nikolopoulos, G. M. and Jex, I.}, title = {{Perfect transfer of multiple excitations in quantum networks (vol 83, artnno 022323, 2011)}}, journal = {{PHYSICAL REVIEW A}}, year = {{2011}}, volume = {{84}}, number = {{3}}, month = {{SEP 16}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Correction}}, language = {{English}}, doi = {{10.1103/PhysRevA.84.039902}}, article-number = {{039902}}, issn = {{1050-2947}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Nikolopoulos, Georgios/H-3023-2011}}, orcid-numbers = {{Nikolopoulos, Georgios/0000-0002-3937-2771}}, number-of-cited-references = {{1}}, times-cited = {{0}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{821WU}}, unique-id = {{ISI:000295005900017}} }
@article{ISI:000295522500016, author = {Lavicka, H. and Potocek, V. and Kiss, T. and Lutz, E. and Jex, I.}, title = {{Quantum walk with jumps}}, journal = {{EUROPEAN PHYSICAL JOURNAL D}}, year = {{2011}}, volume = {{64}}, number = {{1}}, pages = {{119-129}}, month = {{SEP}}, abstract = {{We analyze a special class of 1-D quantum walks (QWs) realized using optical multi-ports. We assume non-perfect multi-ports showing errors in the connectivity, i.e. with a small probability the multi-ports can connect not to their nearest neighbor but to another multi-port at a fixed distance - we call this a jump. We study two cases of QW with jumps where multiple displacements can emerge at one timestep. The first case assumes time-correlated jumps (static disorder). In the second case, we choose the positions of jumps randomly in time (dynamic disorder). The probability distributions of position of the QW walker in both instances differ significantly: dynamic disorder leads to a Gaussian-like distribution, while for static disorder we find two distinct behaviors depending on the parity of jump size. In the case of even-sized jumps, the distribution exhibits a three-peak profile around the position of the initial excitation, whereas the probability distribution in the odd case follows a Laplace-like discrete distribution modulated by additional (exponential) peaks for long times. Finally, our numerical results indicate that by an appropriate mapping a universal functional behavior of the variance of the long-time probability distribution can be revealed with respect to the scaled average of jump size.}}, publisher = {{SPRINGER}}, address = {{233 SPRING ST, NEW YORK, NY 10013 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Lavicka, H (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague 1, Czech Republic. Lavicka, H.; Potocek, V.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Czech Republic. Lavicka, H., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Doppler Inst Math Phys \& Appl Math, CR-11519 Prague 1, Czech Republic. Kiss, T., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, H-1525 Budapest, Hungary. Lutz, E., Univ Augsburg, Dept Phys, D-86135 Augsburg, Germany.}}, doi = {{10.1140/epjd/e2011-20138-8}}, issn = {{1434-6060}}, keywords-plus = {{NONEXTENSIVE STATISTICAL-MECHANICS; DYNAMICAL LOCALIZATION; ABSORPTION PROBLEMS; CELLULAR-AUTOMATA; LIMIT-THEOREMS; ONE-DIMENSION; PAUL TRAP}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{hynek.lavicka@fjfi.cvut.cz}}, researcherid-numbers = {{Lutz, Eric/C-2713-2008 Kiss, Tamas/B-9228-2009}}, funding-acknowledgement = {{MSM {[}6840770039]; MSMT {[}LC 06002]; GACR {[}202/08/H072]; Czech-Hungarian cooperation project (KONTAKT) {[}CZ-11/2009]; Hungarian Scientic Research Fund (OTKA) {[}K83858]; DFG {[}LU1382/1-1]; cluster of excellence Nanosystems Initiative Munich (NIM)}}, funding-text = {{The financial support by MSM 6840770039, MSMT LC 06002, GACR 202/08/H072, the Czech-Hungarian cooperation project (KONTAKT CZ-11/2009), Hungarian Scientic Research Fund (OTKA) under contract No. K83858, the Emmy Noether Program of the DFG (contract No. LU1382/1-1) and the cluster of excellence Nanosystems Initiative Munich (NIM) is gratefully acknowledged.}}, number-of-cited-references = {{43}}, times-cited = {{2}}, journal-iso = {{Eur. Phys. J. D}}, doc-delivery-number = {{828SH}}, unique-id = {{ISI:000295522500016}} }
@article{ISI:000301051200002, author = {Kiss, T. and Vymetal, S. and Toth, L. D. and Gabris, A. and Jex, I. and Alber, G.}, title = {{Measurement-Induced Chaos with Entangled States}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{2011}}, volume = {{107}}, number = {{10}}, month = {{AUG 31}}, abstract = {{The dynamics of an ensemble of identically prepared two-qubit systems is investigated which is subjected to the iteratively applied measurements and conditional selection of a typical entanglement purification protocol. The resulting dynamics exhibits strong sensitivity to initial conditions. For one class of initial states two types of islands characterize the asymptotic limit. They correspond to a separable and a fully entangled two-qubit state, respectively, and their boundaries form fractal-like structures. In the presence of incoherent noise an additional stable asymptotic cycle appears.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Kiss, T (Reprint Author), Res Inst Solid State Phys \& Opt, POB 49, H-1525 Budapest, Hungary. Kiss, T.; Toth, L. D.; Gabris, A., Res Inst Solid State Phys \& Opt, H-1525 Budapest, Hungary. Vymetal, S.; Gabris, A.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, CR-11519 Prague 1, Stare Mesto, Czech Republic. Toth, L. D., Univ Cambridge, DAMTP, Cambridge CB2 1TN, England. Alber, G., Tech Univ Darmstadt, IAP, D-64289 Darmstadt, Germany.}}, doi = {{10.1103/PhysRevLett.107.100501}}, article-number = {{100501}}, issn = {{0031-9007}}, keywords-plus = {{QUANTUM-MECHANICS}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009}}, funding-acknowledgement = {{MSM {[}6840770039]; MSMT {[}LC 06002]; Czech-Hungarian cooperation project (KONTAKT) {[}CZ-11/2009]; Hungarian Scientific Research Fund (OTKA) {[}K83858]}}, funding-text = {{We acknowledge the financial support by MSM 6840770039, MSMT LC 06002, and the Czech-Hungarian cooperation project (KONTAKT, CZ-11/2009) and by the Hungarian Scientific Research Fund (OTKA) under Contract No. K83858.}}, number-of-cited-references = {{21}}, times-cited = {{2}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{902PU}}, unique-id = {{ISI:000301051200002}} }
@article{ISI:000294268000001, author = {Novotny, Jaroslav and Alber, Gernot and Jex, Igor}, title = {{Entanglement and Decoherence: Fragile and Robust Entanglement}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{2011}}, volume = {{107}}, number = {{9}}, month = {{AUG 23}}, abstract = {{The destruction of entanglement of open quantum systems by decoherence is investigated in the asymptotic long-time limit. For this purpose a general and analytically solvable decoherence model is presented which does not involve any weak-coupling or Markovian assumption. It is shown that two fundamentally different classes of entangled states can be distinguished and that they can be influenced significantly by two important environmental properties, namely, its initially prepared state and its size. Quantum states of the first class are fragile against decoherence so that they can be disentangled asymptotically even if coherences between pointer states are still present. Quantum states of the second type are robust against decoherence. Asymptotically they can be disentangled only if also decoherence is perfect. A simple criterion for identifying these two classes on the basis of two-qubit entanglement is presented.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague 1, Stare Mesto, Czech Republic. Novotny, Jaroslav; Jex, Igor, Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Stare Mesto, Czech Republic. Novotny, Jaroslav; Alber, Gernot, Tech Univ Darmstadt, Inst Angewandte Phys, D-64289 Darmstadt, Germany.}}, doi = {{10.1103/PhysRevLett.107.090501}}, article-number = {{090501}}, issn = {{0031-9007}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, funding-acknowledgement = {{Alexander von Humboldt Foundation; CASED; Czech Republic {[}MSM6840770039, MSMT LC06002]}}, funding-text = {{Financial support by the Alexander von Humboldt Foundation, by CASED, and by MSM6840770039 and MSMT LC06002 of the Czech Republic is acknowledged.}}, number-of-cited-references = {{12}}, times-cited = {{5}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{812DM}}, unique-id = {{ISI:000294268000001}} }
@article{ISI:000292002700003, author = {Novotny, J. and Alber, G. and Jex, I.}, title = {{Asymptotic dynamics of qubit networks under randomly applied controlled unitary transformations}}, journal = {{NEW JOURNAL OF PHYSICS}}, year = {{2011}}, volume = {{13}}, month = {{MAY 26}}, abstract = {{The asymptotic dynamics of many-qubit quantum systems is investigated under iteratively and randomly applied unitary transformations. For a one-parameter family of unitary transformations, which entangle pairs of qubits, two main theorems are proved. They characterize completely the dependence of the resulting asymptotic dynamics on the topology of the interaction graph that encodes all possible qubit couplings. These theorems exhibit clearly which aspects of an interaction graph are relevant and which ones are irrelevant to the asymptotic dynamics. On the basis of these theorems, the local entropy transport between an open quantum system and its environment are explored for strong non-Markovian couplings and for different sizes of the environment and different interaction topologies. It is shown that although the randomly applied unitary entanglement operations cannot decrease the overall entropy of such a qubit network, a local entropy decrease or `cooling' of subsystems is possible for special classes of interaction topologies.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Czech Tech Univ, Dept Phys, FNSPE, Brehova 7, Prague 11519 1, Czech Republic. Novotny, J.; Jex, I., Czech Tech Univ, Dept Phys, FNSPE, Prague 11519 1, Czech Republic. Novotny, J.; Alber, G., Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany.}}, doi = {{10.1088/1367-2630/13/5/053052}}, article-number = {{053052}}, issn = {{1367-2630}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{novotny.jaroslav@seznam.cz}}, number-of-cited-references = {{24}}, times-cited = {{3}}, journal-iso = {{New J. Phys.}}, doc-delivery-number = {{782IW}}, unique-id = {{ISI:000292002700003}} }
@article{ISI:000290304800001, author = {Schreiber, A. and Cassemiro, K. N. and Potocek, V. and Gabris, A. and Jex, I. and Silberhorn, Ch.}, title = {{Decoherence and Disorder in QuantumWalks: From Ballistic Spread to Localization}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{2011}}, volume = {{106}}, number = {{18}}, month = {{MAY 6}}, abstract = {{We investigate the impact of decoherence and static disorder on the dynamics of quantum particles moving in a periodic lattice. Our experiment relies on the photonic implementation of a one-dimensional quantum walk. The pure quantum evolution is characterized by a ballistic spread of a photon's wave packet along 28 steps. By applying controlled time-dependent operations we simulate three different environmental influences on the system, resulting in a fast ballistic spread, a diffusive classical walk, and the first Anderson localization in a discrete quantum walk architecture.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Schreiber, A (Reprint Author), Max Planck Inst Sci Light, Gunther Scharowsky Str 1 Bau 24, D-91058 Erlangen, Germany. Schreiber, A.; Cassemiro, K. N.; Silberhorn, Ch., Max Planck Inst Sci Light, D-91058 Erlangen, Germany. Potocek, V.; Gabris, A.; Jex, I., Czech Tech Univ, FNSPE, Dept Phys, Prague 11519, Czech Republic. Silberhorn, Ch., Univ Paderborn, D-33098 Paderborn, Germany.}}, doi = {{10.1103/PhysRevLett.106.180403}}, article-number = {{180403}}, issn = {{0031-9007}}, keywords-plus = {{ANDERSON LOCALIZATION; WALKS; LATTICES}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{Andreas.Schreiber@mpl.mpg.de}}, researcherid-numbers = {{Gabris, Aurel/A-7615-2008 1, INCT/G-5846-2013 Informacao quantica, Inct/H-9493-2013 Silberhorn, Christine/J-4919-2013}}, orcid-numbers = {{Silberhorn, Christine/0000-0002-2349-5443}}, funding-acknowledgement = {{German Israel Foundation {[}970/2007]; AvH Foundation; OTKA {[}T83858]; {[}MSMT LC06002]; {[}MSM 6840770039]; {[}SGS10/294/OHK4/3T/14]}}, funding-text = {{We thank P. P. Rohde for helpful discussions. We acknowledge financial support from the German Israel Foundation (Project No. 970/2007). K. N. C. and I. J. acknowledge support from the AvH Foundation; V. P., A. G., and I. J. from MSMT LC06002 and MSM 6840770039; V. P. from SGS10/294/OHK4/3T/14; and A. G. from OTKA T83858.}}, number-of-cited-references = {{30}}, times-cited = {{69}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{760DT}}, unique-id = {{ISI:000290304800001}} }
@article{ISI:000289065200001, author = {Stefanak, M. and Barnett, S. M. and Kollar, B. and Kiss, T. and Jex, I.}, title = {{Directional correlations in quantum walks with two particles}}, journal = {{NEW JOURNAL OF PHYSICS}}, year = {{2011}}, volume = {{13}}, month = {{MAR 21}}, abstract = {{Quantum walks on a line with a single particle possess a classical analogue. Involving more walkers opens up the possibility of studying collective quantum effects, such as many-particle correlations. In this context, entangled initial states and the indistinguishability of the particles play a role. We consider the directional correlations between two particles performing a quantum walk on a line. For non-interacting particles, we find analytic asymptotic expressions and give the limits of directional correlations. We show that by introducing delta-interaction between the particles, one can exceed the limits for non-interacting particles.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague 1, Stare Mesto, Czech Republic. Stefanak, M.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Stare Mesto, Czech Republic. Barnett, S. M., Univ Strathclyde, Dept Phys, Glasgow G4 0NG, Lanark, Scotland. Kollar, B.; Kiss, T., Hungarian Acad Sci, Dept Quantum Opt \& Quantum Informat, Res Inst Solid State Phys \& Opt, H-1121 Budapest, Hungary.}}, doi = {{10.1088/1367-2630/13/3/033029}}, article-number = {{033029}}, issn = {{1367-2630}}, keywords-plus = {{ALGORITHMS; SEARCH}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{martin.stefanak@fjfi.cvut.cz}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012 Kollar, Balint/J-2297-2012}}, funding-acknowledgement = {{MSM {[}6840770039]; MSMT LC {[}06002]; Czech-Hungarian cooperation project (KONTAKT) {[}CZ-11/2009]; Royal Society; Wolfson Foundation}}, funding-text = {{Financial support from MSM 6840770039, MSMT LC 06002 and the Czech-Hungarian cooperation project (KONTAKT, CZ-11/2009) is gratefully acknowledged. SMB thanks the Royal Society and the Wolfson Foundation for support.}}, number-of-cited-references = {{66}}, times-cited = {{10}}, journal-iso = {{New J. Phys.}}, doc-delivery-number = {{744AV}}, unique-id = {{ISI:000289065200001}} }
@article{ISI:000287711800003, author = {Brougham, T. and Nikolopoulos, G. M. and Jex, I.}, title = {{Perfect transfer of multiple excitations in quantum networks}}, journal = {{PHYSICAL REVIEW A}}, year = {{2011}}, volume = {{83}}, number = {{2}}, month = {{FEB 24}}, abstract = {{We present a general formalism to the problem of perfect state transfer (PST), where the state involves multiple excitations of the quantum network. A key feature of our formalism is that it allows for inclusion of nontrivial interactions between the excitations. Hence, it is perfectly suited to addressing the problem of PST in the context of various types of physical realizations. The general formalism is also flexible enough to account for situations where multiple excitations are ``focused{''} onto the same site.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Brougham, T (Reprint Author), Czech Tech Univ, Dept Phys, FNSPE, Brehova 7, CZ-11519 Prague 1, Czech Republic. Brougham, T.; Jex, I., Czech Tech Univ, Dept Phys, FNSPE, CZ-11519 Prague 1, Czech Republic. Nikolopoulos, G. M., FORTH, Inst Elect Struct \& Laser, GR-71110 Iraklion, Crete, Greece.}}, doi = {{10.1103/PhysRevA.83.022323}}, article-number = {{022323}}, issn = {{1050-2947}}, keywords-plus = {{STATE TRANSFER; DYNAMICS; ENTANGLEMENT; CHAIN; DOTS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Nikolopoulos, Georgios/H-3023-2011}}, orcid-numbers = {{Nikolopoulos, Georgios/0000-0002-3937-2771}}, funding-acknowledgement = {{Doppler Institute; EC RTN EMALI {[}MRTN-CT-2006-035369]; {[}MSM6840770039]; {[}MSMT LC06002]}}, funding-text = {{T.B. and I.J. acknowledge financial support from the Doppler Institute and from Grants No. MSM6840770039 and MSMT LC06002 of the Czech Republic. G.M.N. acknowledges support from the EC RTN EMALI (Contract No. MRTN-CT-2006-035369).}}, number-of-cited-references = {{20}}, times-cited = {{4}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{726HU}}, unique-id = {{ISI:000287711800003}} }
@inproceedings{ISI:000302005200033, author = {Schreiber, A. and Cassemiro, K. N. and Potocek, V. and Gabris, A. and Jex, I. and Silberhorn, Ch}, editor = {{Ralph, T and Lam, PK}}, title = {{Photonic quantum walks in a fiber based recursion loop}}, booktitle = {{QUANTUM COMMUNICATION, MEASUREMENT AND COMPUTING (QCMC): THE TENTH INTERNATIONAL CONFERENCE}}, series = {{AIP Conference Proceedings}}, year = {{2011}}, volume = {{1363}}, note = {{10th International Conference on Quantum Communication, Measurement and Computing (QCMC), Brisbane, AUSTRALIA, JUL 19-23, 2010}}, organization = {{Australian Res Council Ctr Excellence Quantum Comp Technol; Tamagawa Univ; Australian Res Council Ctr Excellence Quantum-Atom Opt; Res Lab Elect Massachusetts Inst Technol; NewSpec Pty Ltd; Oxford Instruments Pty Ltd; Lastek Australia, Toptica Photon}}, abstract = {{We present a flexible and robust system for implementing one-dimensional coined quantum walks. A recursion loop in the optical network together with a translation of the spatial into the time domain ensures the possible increment of the step number without need of additional optical elements. An intrinsic phase stability assures a high degree of coherence and hence guarantees a good scalability of the system. We performed a quantum walk over 27 steps and analyzed the 54 output modes. Furthermore, we estimated that up to 100 steps can be realized with only minor changes in the used components.}}, publisher = {{AMER INST PHYSICS}}, address = {{2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{Schreiber, A (Reprint Author), Max Planck Inst Sci Light, Gunther Scharowsky Str 1,Bau 24, D-91058 Erlangen, Germany. Schreiber, A.; Cassemiro, K. N.; Silberhorn, Ch, Max Planck Inst Sci Light, D-91058 Erlangen, Germany.}}, doi = {{10.1063/1.3630170}}, issn = {{0094-243X}}, isbn = {{978-0-7354-0921-7}}, keywords = {{Quantum walk; Quantum simulations}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Mathematical}}, researcherid-numbers = {{Silberhorn, Christine/J-4919-2013}}, orcid-numbers = {{Silberhorn, Christine/0000-0002-2349-5443}}, number-of-cited-references = {{10}}, times-cited = {{0}}, doc-delivery-number = {{BZM24}}, unique-id = {{ISI:000302005200033}} }
@article{ISI:000288903600015, author = {Hamilton, Craig S. and Gabris, Aurel and Jex, Igor and Barnett, Stephen M.}, title = {{Quantum walk with a four-dimensional coin}}, journal = {{NEW JOURNAL OF PHYSICS}}, year = {{2011}}, volume = {{13}}, month = {{JAN}}, abstract = {{We examine the physical implementation of a discrete time quantum walk with a four-dimensional coin. Our quantum walker is a photon moving repeatedly through a time delay loop, with time being our position space. The quantum coin is implemented using the internal states of the photon: the polarization and two of the orbital angular momentum states. We demonstrate how to implement this physically and what components would be needed. We then illustrate some of the results that could be obtained by performing the experiment.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Hamilton, CS (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague, Czech Republic. Hamilton, Craig S.; Gabris, Aurel; Jex, Igor; Barnett, Stephen M., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic. Barnett, Stephen M., Univ Strathclyde, Dept Phys, SUPA, Glasgow G4 0NG, Lanark, Scotland.}}, doi = {{10.1088/1367-2630/13/1/013015}}, article-number = {{013015}}, issn = {{1367-2630}}, keywords-plus = {{ORBITAL ANGULAR-MOMENTUM; POLARIZATION; STATES; MODES; LIGHT}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{craig.hamilton@fjfi.cvut.cz}}, researcherid-numbers = {{Gabris, Aurel/A-7615-2008}}, funding-acknowledgement = {{Doppler Institute; FNSPE CTU in Prague; Royal Society; Wolfram Foundation; {[}MSM6840770039]; {[}MSMT LC06002]}}, funding-text = {{We gratefully acknowledge helpful discussions with Professor C Silberhorn, Dr K Cassemiro and Mr A Schreiber. CSH, AG and IJ acknowledge financial support from the Doppler Institute, FNSPE CTU in Prague and from grants MSM6840770039 and MSMT LC06002 of the Czech Republic. SMB thanks the Royal Society and the Wolfram Foundation for financial support.}}, number-of-cited-references = {{32}}, times-cited = {{9}}, journal-iso = {{New J. Phys.}}, doc-delivery-number = {{741YK}}, unique-id = {{ISI:000288903600015}} }
@article{ISI:000288550100027, author = {Brougham, T. and Kost'ak, V. and Jex, I. and Andersson, E. and Kiss, T.}, title = {{Entanglement preparation using symmetric multiports}}, journal = {{EUROPEAN PHYSICAL JOURNAL D}}, year = {{2011}}, volume = {{61}}, number = {{1}}, pages = {{231-236}}, month = {{JAN}}, abstract = {{We investigate the entanglement produced by a multi-path interferometer that is composed of two symmetric multiports, with phase shifts applied to the output of the first multiport. Particular attention is paid to the case when we have a single photon entering the interferometer. For this situation we derive a simple condition that characterizes the types of entanglement that one can generate. We then show how one can use the results from the single-photon case to determine what kinds of multi-photon entangled states one can prepare using the interferometer.}}, publisher = {{SPRINGER}}, address = {{233 SPRING ST, NEW YORK, NY 10013 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Brougham, T (Reprint Author), Czech Tech Univ, Dept Phys, FNSPE, Brehova 7, Prague 11519 1, Czech Republic. Brougham, T.; Kost'ak, V.; Jex, I., Czech Tech Univ, Dept Phys, FNSPE, Prague 11519 1, Czech Republic. Andersson, E., Heriot Watt Univ, Dept Phys, SUPA, Sch EPS, Edinburgh, Midlothian, Scotland. Kiss, T., Hungarian Acad Sci, Dept Quantum Opt \& Quantum Informat, Res Inst Solid State Phys \& Opt, H-1121 Budapest, Hungary.}}, doi = {{10.1140/epjd/e2010-10337-2}}, issn = {{1434-6060}}, keywords-plus = {{QUANTUM-THEORY; PARTICLE; STATE}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{thomas.brougham@gmail.com}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Andersson, Erika/D-1139-2013}}, orcid-numbers = {{Andersson, Erika/0000-0001-5856-6806}}, funding-acknowledgement = {{Royal Society {[}2006/R2IJP]; Czech Hungarian project {[}MEB 041011 (CZ-11/2009)]; Doppler Institute; Czech Republic {[}MSM 6840770039, MSMT LC06002]}}, funding-text = {{We acknowledge financial support from the Royal Society International Joint Project grant 2006/R2IJP and the Czech Hungarian project grant MEB 041011 (CZ-11/2009); T.B., V.K. and I.J. also acknowledge financial support from the Doppler Institute and from grants MSM 6840770039 and MSMT LC06002 of the Czech Republic.}}, number-of-cited-references = {{30}}, times-cited = {{2}}, journal-iso = {{Eur. Phys. J. D}}, doc-delivery-number = {{737DX}}, unique-id = {{ISI:000288550100027}} }
@article{ISI:000288903600001, author = {Rohde, Peter P. and Schreiber, Andreas and Stefanak, Martin and Jex, Igor and Silberhorn, Christine}, title = {{Multi-walker discrete time quantum walks on arbitrary graphs, their properties and their photonic implementation}}, journal = {{NEW JOURNAL OF PHYSICS}}, year = {{2011}}, volume = {{13}}, month = {{JAN}}, abstract = {{Quantum walks have emerged as an interesting alternative to the usual circuit model for quantum computing. While still universal for quantum computing, the quantum walk model has very different physical requirements, which lends itself more naturally to some physical implementations, such as linear optics. Numerous authors have considered walks with one or two walkers, on one-dimensional graphs, and several experimental demonstrations have been performed. In this paper, we discuss generalizing the model of discrete time quantum walks to the case of an arbitrary number of walkers acting on arbitrary graph structures. We present a formalism that allows for the analysis of such situations, and several example scenarios for how our techniques can be applied. We consider the most important features of quantum walks-measurement, distinguishability, characterization and the distinction between classical and quantum interference. We also discuss the potential for physical implementation in the context of linear optics, which is of relevance to present-day experiments.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Rohde, PP (Reprint Author), Max Planck Inst Sci Light, Erlangen, Germany. Rohde, Peter P.; Schreiber, Andreas; Silberhorn, Christine, Max Planck Inst Sci Light, Erlangen, Germany. Rohde, Peter P., Univ Queensland, Ctr Quantum Comp Technol, Brisbane, Qld 4072, Australia. Stefanak, Martin; Jex, Igor, Czech Tech Univ, Fac Nucl Sci Phys Engn, Dept Phys, CR-16635 Prague, Czech Republic. Silberhorn, Christine, Univ Paderborn, Paderborn, Germany.}}, doi = {{10.1088/1367-2630/13/1/013001}}, article-number = {{013001}}, issn = {{1367-2630}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{dr.rohde@gmail.com}}, researcherid-numbers = {{Stefanak, Martin/G-5239-2012 Silberhorn, Christine/J-4919-2013}}, orcid-numbers = {{Silberhorn, Christine/0000-0002-2349-5443}}, funding-acknowledgement = {{Australian Research Council; Czech Ministry of Education {[}MSM6840770039, MSMT LC06002]; German Israel Foundation {[}970/2007]}}, funding-text = {{We acknowledge Andreas Eckstein, Malte Avenhaus, Aurel Gabris and Vaclav Potocek for very helpful discussions and Andreas Christ and Katiuscia Cassemiro for immeasurably helpful discussions and critique. PR acknowledges support from the Australian Research Council. MS and IJ acknowledge grant support from the Czech Ministry of Education (MSM6840770039 and MSMT LC06002). We acknowledge the German Israel Foundation (project 970/2007) for financial support. While the manuscript was under preparation, Peruzzo et al {[}16] experimentally demonstrated an optical implementation of a two-photon quantum walk, which overlaps with the techniques presented here.}}, number-of-cited-references = {{26}}, times-cited = {{27}}, journal-iso = {{New J. Phys.}}, doc-delivery-number = {{741YK}}, unique-id = {{ISI:000288903600001}} }
@inproceedings{ISI:000291306100018, author = {Kecskes, L. and Kiss, T. and Stefanak, M. and Jex, I.}, editor = {{Prochazka, I and Sobolewski, R and Fiurasek, J}}, title = {{The role of measurement in the recurrence property of discrete timed quantum walks}}, booktitle = {{PHOTON COUNTING APPLICATIONS, QUANTUM OPTICS, AND QUANTUM INFORMATION TRANSFER AND PROCESSING III}}, series = {{Proceedings of SPIE}}, year = {{2011}}, volume = {{8072}}, note = {{Conference on the Photon Counting Applications, Quantum Optics, and Quantum Information Transfer and Processing III, Prague, CZECH REPUBLIC, APR 18-20, 2011}}, organization = {{SPIE}}, abstract = {{The quantum mechanical generalisation of random walks (called Quantum Walks) present us with a broader spectrum of possibilities compared to their classical counterparts. The aim of the presented study is to explore a new portion of this area by incorporating a new step in the process of the Quantum Walk unique to quantum mechanics: the measurement. Our focus lies in the characterising number of the recurrence behaviour of the walk (Polya-number). We observe the effect of the standard projective measurement, a yes-no measurement on the origin and the effect of different measurement schemes (periodic and random) on the definition and the numeric value of the Polya-number.}}, publisher = {{SPIE-INT SOC OPTICAL ENGINEERING}}, address = {{1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{Kecskes, L (Reprint Author), Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Konkoly Thege M 29-33, H-1211 Budapest, Hungary. Kecskes, L.; Kiss, T., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, H-1211 Budapest, Hungary.}}, doi = {{10.1117/12.886813}}, article-number = {{80720U}}, issn = {{0277-786X}}, isbn = {{978-0-81948-662-2}}, research-areas = {{Engineering; Optics}}, web-of-science-categories = {{Engineering, Electrical \& Electronic; Optics}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012}}, number-of-cited-references = {{5}}, times-cited = {{0}}, doc-delivery-number = {{BVE53}}, unique-id = {{ISI:000291306100018}} }
@article{ISI:000282330000019, author = {Novotny, Jaroslav and Alber, Gernot and Jex, Igor}, title = {{Asymptotic evolution of random unitary operations}}, journal = {{CENTRAL EUROPEAN JOURNAL OF PHYSICS}}, year = {{2010}}, volume = {{8}}, number = {{6}}, pages = {{1001-1014}}, month = {{DEC}}, abstract = {{We analyze the asymptotic dynamics of quantum systems resulting from large numbers of iterations of random unitary operations. Although, in general, these quantum operations cannot be diagonalized it is shown that their resulting asymptotic dynamics is described by a diagonalizable superoperator. We prove that this asymptotic dynamics takes place in a typically low dimensional attractor space which is independent of the probability distribution of the unitary operations applied. This vector space is spanned by all eigenvectors of the unitary operations involved which are associated with eigenvalues of unit modulus. Implications for possible asymptotic dynamics of iterated random unitary operations are presented and exemplified in an example involving random controlled-not operations acting on two qubits.}}, publisher = {{VERSITA}}, address = {{SOLIPSKA 14A-1, 02-482 WARSAW, POLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Tech Univ Darmstadt, Inst Angew Phys, Hsch Str 4A, D-64289 Darmstadt, Germany. Novotny, Jaroslav; Alber, Gernot, Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany. Novotny, Jaroslav; Jex, Igor, FJFI CVUT Praze, Dept Phys, Prague 11519, Czech Republic.}}, doi = {{10.2478/s11534-010-0018-8}}, issn = {{1895-1082}}, eissn = {{1644-3608}}, keywords = {{random unitary map; asymptotic evolution; iterations; attractor; open dynamics}}, keywords-plus = {{COMPLEX NETWORKS}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{novotny.jaroslav@seznam.cz}}, funding-acknowledgement = {{Czech Ministry of Education {[}MSM 6840770039, MSMT LC 06002]; Alexander von Humboldt Foundation; DAAD; CASED}}, funding-text = {{Financial support by the Czech Ministry of Education (by MSM 6840770039 and MSMT LC 06002), by the Alexander von Humboldt Foundation, by the DAAD, and by CASED is gratefully acknowledged.}}, number-of-cited-references = {{18}}, times-cited = {{9}}, journal-iso = {{Cent. Eur. J. Phys.}}, doc-delivery-number = {{656KB}}, unique-id = {{ISI:000282330000019}} }
@article{ISI:000284693600013, author = {Adam, P. and Kiss, T. and Darazs, Z. and Jex, I.}, title = {{Conditional generation of optical Schrodinger cat states}}, journal = {{PHYSICA SCRIPTA}}, year = {{2010}}, volume = {{T140}}, month = {{SEP}}, note = {{16th Central European Workshop on Quantum Optics, Turku, FINLAND, MAY 23-27, 2009}}, abstract = {{Given a source of two coherent state superpositions with small separation in a travelling wave optical setting, we show that by interference and balanced homodyne measurement it is possible to conditionally prepare a symmetrically placed superposition of coherent states around the origin of the phase space. The separation of coherent states in the superposition will be amplified during the process.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article; Proceedings Paper}}, language = {{English}}, affiliation = {{Adam, P (Reprint Author), Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Dept Quantum Opt \& Quantum Informat, Konkoly Thege M U 29-33, H-1121 Budapest, Hungary. Adam, P.; Kiss, T.; Darazs, Z., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Dept Quantum Opt \& Quantum Informat, H-1121 Budapest, Hungary. Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Stare Mesto, Czech Republic.}}, doi = {{10.1088/0031-8949/2010/T140/014011}}, article-number = {{014011}}, issn = {{0031-8949}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{adam@szfki.hu}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Darazs, Zoltan/C-8062-2013}}, orcid-numbers = {{Darazs, Zoltan/0000-0002-4795-1677}}, number-of-cited-references = {{13}}, times-cited = {{1}}, journal-iso = {{Phys. Scr.}}, doc-delivery-number = {{686JW}}, unique-id = {{ISI:000284693600013}} }
@article{ISI:000284693600037, author = {Stefanak, M. and Kollar, B. and Kiss, T. and Jex, I.}, title = {{Full revivals in 2D quantum walks}}, journal = {{PHYSICA SCRIPTA}}, year = {{2010}}, volume = {{T140}}, month = {{SEP}}, note = {{16th Central European Workshop on Quantum Optics, Turku, FINLAND, MAY 23-27, 2009}}, abstract = {{Recurrence of a random walk is described by the Polya number. For quantum walks, recurrence is understood as the return of the walker to the origin, rather than the full revival of its quantum state. Localization for two-dimensional quantum walks is known to exist in the sense of non-vanishing probability distribution in the asymptotic limit. We show, on the example of the 2D Grover walk, that one can exploit the effect of localization to construct stationary solutions. Moreover, we find full revivals of a quantum state with a period of two steps. We prove that there cannot be longer cycles for a four-state quantum walk. Stationary states and revivals result from interference, which has no counterpart in classical random walks.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article; Proceedings Paper}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), FJFI CVUT Praze, Dept Phys, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Stefanak, M.; Jex, I., FJFI CVUT Praze, Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic. Kollar, B.; Kiss, T., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Dept Quantum Opt \& Quantum Informat, H-1121 Budapest, Hungary.}}, doi = {{10.1088/0031-8949/2010/T140/014035}}, article-number = {{014035}}, issn = {{0031-8949}}, keywords-plus = {{CELLULAR-AUTOMATA}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{martin.stefanak@fjfi.cvut.cz}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012 Kollar, Balint/J-2297-2012}}, number-of-cited-references = {{21}}, times-cited = {{7}}, journal-iso = {{Phys. Scr.}}, doc-delivery-number = {{686JW}}, unique-id = {{ISI:000284693600037}} }
@article{ISI:000279539300002, author = {Kollar, B. and Stefanak, M. and Kiss, T. and Jex, I.}, title = {{Recurrences in three-state quantum walks on a plane}}, journal = {{PHYSICAL REVIEW A}}, year = {{2010}}, volume = {{82}}, number = {{1}}, month = {{JUL 6}}, abstract = {{We analyze the role of dimensionality in the time evolution of discrete-time quantum walks through the example of the three-state walk on a two-dimensional triangular lattice. We show that the three-state Grover walk does not lead to trapping (localization) or recurrence to the origin, in sharp contrast to the Grover walk on the two-dimensional square lattice. We determine the power-law scaling of the probability at the origin with the method of stationary phase. We prove that only a special subclass of coin operators can lead to recurrence, and there are no coins that lead to localization. The propagation for the recurrent subclass of coins is quasi-one dimensional.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague 1, Stare Mesto, Czech Republic. Stefanak, M.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Stare Mesto, Czech Republic. Kollar, B.; Kiss, T., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Dept Quantum Opt \& Quantum Informat, H-1121 Budapest, Hungary.}}, doi = {{10.1103/PhysRevA.82.012303}}, article-number = {{012303}}, issn = {{1050-2947}}, keywords-plus = {{LATTICE}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{martin.stefanak@fjfi.cvut.cz tkiss-libri@szfki.hu}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012 Kollar, Balint/J-2297-2012}}, funding-acknowledgement = {{MSM {[}6840770039]; MSMT {[}LC 06002]; Czech-Hungarian cooperation Project {[}MEB041011, CZ-11/2009]}}, funding-text = {{T.K. thanks Gyorgy Kali and Misha Titov for interesting discussions. The financial support by MSM Grant No. 6840770039, MSMT Grant No. LC 06002, and the Czech-Hungarian cooperation Project No. (MEB041011, CZ-11/2009) is gratefully acknowledged.}}, number-of-cited-references = {{30}}, times-cited = {{11}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{620YN}}, unique-id = {{ISI:000279539300002}} }
@article{ISI:000274336800006, author = {Schreiber, A. and Cassemiro, K. N. and Potocek, V. and Gabris, A. and Mosley, P. J. and Andersson, E. and Jex, I. and Silberhorn, Ch.}, title = {{Photons Walking the Line: A Quantum Walk with Adjustable Coin Operations}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{2010}}, volume = {{104}}, number = {{5}}, month = {{FEB 5}}, abstract = {{We present the first robust implementation of a coined quantum walk over five steps using only passive optical elements. By employing a fiber network loop we keep the amount of required resources constant as the walker's position Hilbert space is increased. We observed a non-Gaussian distribution of the walker's final position, thus characterizing a faster spread of the photon wave packet in comparison to the classical random walk. The walk is realized for many different coin settings and initial states, opening the way for the implementation of a quantum-walk-based search algorithm.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Schreiber, A (Reprint Author), Max Planck Inst Sci Light, Gunther Scharowsky Str 1 Bau 24, D-91058 Erlangen, Germany. Schreiber, A.; Cassemiro, K. N.; Mosley, P. J.; Silberhorn, Ch., Max Planck Inst Sci Light, D-91058 Erlangen, Germany. Potocek, V.; Gabris, A.; Jex, I., Czech Tech Univ, Dept Phys, FNSPE, Prague 11519, Czech Republic. Andersson, E., Heriot Watt Univ, Sch EPS, SUPA, Edinburgh EH14 4AS, Midlothian, Scotland.}}, doi = {{10.1103/PhysRevLett.104.050502}}, article-number = {{050502}}, issn = {{0031-9007}}, keywords-plus = {{EXPERIMENTAL REALIZATION}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{Katiuscia.Cassemiro@mpl.mpg.de}}, researcherid-numbers = {{Gabris, Aurel/A-7615-2008 Andersson, Erika/D-1139-2013 Silberhorn, Christine/J-4919-2013}}, orcid-numbers = {{Andersson, Erika/0000-0001-5856-6806 Silberhorn, Christine/0000-0002-2349-5443}}, funding-acknowledgement = {{German Israel Foundation {[}970/2007]; Alexander von Humboldt Foundation; Hungarian Scientific Research Fund {[}T049234, NF068736]; Royal Society {[}2006/R2-IJP]; {[}MT LC06002]; {[}MSM 6840770039]; {[}CZ-10/2007]; {[}GA CR 202/08/H078]}}, funding-text = {{We acknowledge financial support from the German Israel Foundation (Project 970/2007). K. N. C. and I. J. acknowledge financial support from the Alexander von Humboldt Foundation; V. P., A. G., and I. J. from MS. MT LC06002, MSM 6840770039, and CZ-10/2007; V. P. from GA CR 202/08/H078; A. G. from the Hungarian Scientific Research Fund (T049234 and NF068736); E. A., I. J., V. P., and A. G. from the Royal Society International Joint Project Grant No. 2006/R2-IJP.}}, number-of-cited-references = {{29}}, times-cited = {{131}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{553AM}}, unique-id = {{ISI:000274336800006}} }
@article{ISI:000277856200008, author = {Brougham, Thomas and Barnett, Stephen M. and Jex, Igor}, title = {{Interference of composite bosons}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{2010}}, volume = {{57}}, number = {{7}}, pages = {{587-594}}, abstract = {{We investigate multi-boson interference. A Hamiltonian is presented that treats pairs of bosons as a single composite boson. This Hamiltonian allows two pairs of bosons to interact as if they were two single composite bosons. We show that this leads to the composite bosons exhibiting novel interference effects, such as Hong-Ou-Mandel interference. We then investigate generalisations of the formalism to the case of interference between two general composite bosons. Finally, we show how one can realise interference between composite bosons in the two-atom Dicke model.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Brougham, T (Reprint Author), Czech Tech Univ, Dept Phys, FNSPE, Brehova 7, Prague 11519 1, Czech Republic. Brougham, Thomas; Barnett, Stephen M.; Jex, Igor, Czech Tech Univ, Dept Phys, FNSPE, Prague 11519 1, Czech Republic. Barnett, Stephen M., Univ Strathclyde, SUPA, Dept Phys, Glasgow G4 ONG, Lanark, Scotland.}}, doi = {{10.1080/09500340.2010.481731}}, issn = {{0950-0340}}, keywords = {{interference of bosons; quantum optics; Hong-Ou-Mandel effect}}, keywords-plus = {{DIRECTIONAL COUPLER; NONCLASSICAL LIGHT; QUANTUM STATES; CONVERSION}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, author-email = {{thomas.brougham@gmail.com}}, funding-acknowledgement = {{Doppler Institute of the Czech Republic; Royal Society; Wolfson Foundation; Czech Republic Grants {[}MSM6840770039, MSMT LC06002]}}, funding-text = {{We acknowledge financial support from the Doppler Institute and from Grants MSM6840770039 and MSMT LC06002 of the Czech Republic. S. M. B. thanks the Royal Society and the Wolfson Foundation for financial support.}}, number-of-cited-references = {{25}}, times-cited = {{2}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{598RP}}, unique-id = {{ISI:000277856200008}} }
@article{ISI:000272310000060, author = {Brougham, T. and Nikolopoulos, G. M. and Jex, I.}, title = {{Communication in quantum networks of logical bus topology}}, journal = {{PHYSICAL REVIEW A}}, year = {{2009}}, volume = {{80}}, number = {{5}}, month = {{NOV}}, abstract = {{Perfect state transfer (PST) is discussed in the context of passive quantum networks with logical bus topology, where many logical nodes communicate using the same shared media without any external control. The conditions under which a number of point-to-point PST links may serve as building blocks for the design of such multinode networks are investigated. The implications of our results are discussed in the context of various Hamiltonians that act on the entire network and are capable of providing PST between the logical nodes of a prescribed set in a deterministic manner.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Brougham, T (Reprint Author), FJFI CVUT Praze, Dept Phys, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Brougham, T.; Jex, I., FJFI CVUT Praze, Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic. Nikolopoulos, G. M., FORTH, Inst Elect Struct \& Laser, Iraklion 71110, Crete, Greece.}}, doi = {{10.1103/PhysRevA.80.052325}}, article-number = {{052325}}, issn = {{1050-2947}}, keywords = {{information theory; quantum communication; topology}}, keywords-plus = {{ELECTRON WAVEPACKET PROPAGATION; DYNAMICS; ENTANGLEMENT; CHAIN; DOTS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Nikolopoulos, Georgios/H-3023-2011}}, orcid-numbers = {{Nikolopoulos, Georgios/0000-0002-3937-2771}}, number-of-cited-references = {{30}}, times-cited = {{7}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{526RH}}, unique-id = {{ISI:000272310000060}} }
@article{ISI:000268043300011, author = {Marzoli, I. and Tombesi, P. and Ciaramicoli, G. and Werth, G. and Bushev, P. and Stahl, S. and Schmidt-Kaler, F. and Hellwig, M. and Henkel, C. and Marx, G. and Jex, I. and Stachowska, E. and Szawiola, G. and Walaszyk, A.}, title = {{Experimental and theoretical challenges for the trapped electron quantum computer}}, journal = {{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}}, year = {{2009}}, volume = {{42}}, number = {{15}}, month = {{AUG 14}}, abstract = {{We discuss quantum information processing with trapped electrons. After recalling the operation principle of planar Penning traps, we sketch the experimental conditions to load, cool and detect single electrons. Here we present a detailed investigation of a scalable scheme including feasibility studies and the analysis of all important elements, relevant for the experimental stage. On the theoretical side, we discuss different methods to couple electron qubits. We estimate the relevant qubit coherence times and draw implications for the experimental setting. A critical assessment of quantum information processing with trapped electrons concludes the paper.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND}}, type = {{Review}}, language = {{English}}, affiliation = {{Marzoli, I (Reprint Author), Univ Camerino, Dipartimento Fis, I-62032 Camerino, Italy. Marzoli, I.; Tombesi, P.; Ciaramicoli, G., Univ Camerino, Dipartimento Fis, I-62032 Camerino, Italy. Werth, G.; Bushev, P.; Stahl, S., Johannes Gutenberg Univ Mainz, Dept Phys, D-55099 Mainz, Germany. Schmidt-Kaler, F.; Hellwig, M., Univ Ulm, D-89069 Ulm, Germany. Henkel, C., Univ Potsdam, Inst Phys \& Astron, D-14476 Potsdam, Germany. Marx, G., Ernst Moritz Arndt Univ Greifswald, D-17489 Greifswald, Germany. Jex, I., FJFI CVUT, Dept Phys, Prague 11519, Czech Republic. Stachowska, E.; Szawiola, G.; Walaszyk, A., Poznan Tech Univ, PL-60965 Poznan, Poland.}}, doi = {{10.1088/0953-4075/42/15/154010}}, article-number = {{154010}}, issn = {{0953-4075}}, keywords-plus = {{PLANAR PENNING TRAP; IONS; COMPUTATION; GATE; CYCLOTRON; PARTICLES; ALGORITHM; PULSES; DOTS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{irene.marzoli@unicam.it}}, researcherid-numbers = {{Henkel, Carsten/C-2540-2011 Szawiola, Gustaw/H-1575-2014}}, funding-acknowledgement = {{European Union {[}FP6-003772]}}, funding-text = {{We acknowledge financial support by the European Union within the sixth framework programme (contract no. FP6-003772).}}, number-of-cited-references = {{68}}, times-cited = {{14}}, journal-iso = {{J. Phys. B-At. Mol. Opt. Phys.}}, doc-delivery-number = {{471GF}}, unique-id = {{ISI:000268043300011}} }
@article{ISI:000267403500003, author = {Novotny, J. and Alber, G. and Jex, I.}, title = {{Random unitary dynamics of quantum networks}}, journal = {{JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL}}, year = {{2009}}, volume = {{42}}, number = {{28}}, month = {{JUL 17}}, abstract = {{We investigate the asymptotic dynamics of quantum networks under repeated applications of random unitary operations. It is shown that in the asymptotic limit of large numbers of iterations this dynamics is generally governed by a typically low dimensional attractor space. This space is determined completely by the unitary operations involved and it is independent of the probabilities with which these unitary operations are applied. Based on this general feature analytical results are presented for the asymptotic dynamics of arbitrarily large cyclic qubit networks whose nodes are coupled by randomly applied controlled-NOT operations.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Tech Univ Darmstadt, Inst Angew Phys, Petersenstr 30, D-64289 Darmstadt, Germany. Novotny, J.; Alber, G., Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany. Novotny, J.; Jex, I., Czech Tech Univ, Dept Phys, Prague 11519 1, Czech Republic.}}, doi = {{10.1088/1751-8113/42/28/282003}}, article-number = {{282003}}, issn = {{1751-8113}}, eissn = {{1751-8121}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary; Physics, Mathematical}}, author-email = {{gernot.alber@physik.t-darmstadt.de}}, funding-acknowledgement = {{DAAD; Alexander von Humboldt Foundation; Czech Republic {[}MSM6840770039, MSMT LC06002]}}, funding-text = {{Financial support by the DAAD, by the Alexander von Humboldt Foundation, and by MSM6840770039 and MSMT LC06002 of the Czech Republic is acknowledged.}}, number-of-cited-references = {{14}}, times-cited = {{11}}, journal-iso = {{J. Phys. A-Math. Theor.}}, doc-delivery-number = {{463BN}}, unique-id = {{ISI:000267403500003}} }
@article{ISI:000269768300057, author = {Kiss, T. and Kecskes, L. and Stefanak, M. and Jex, I.}, title = {{Recurrence in coined quantum walks}}, journal = {{PHYSICA SCRIPTA}}, year = {{2009}}, volume = {{T135}}, month = {{JUL}}, note = {{15th Central European Workshop on Quantum Optics, Belgrade, SERBIA, MAY 29-JUN 03, 2008}}, abstract = {{Recurrence of quantum walks on lattices can be characterized by the generalized Polya number. Its value reflects the difference between a classical and a quantum system. The dimension of the lattice is not a unique parameter in the quantum case; both the coin operator and the initial quantum state of the coin influence the recurrence in a nontrivial way. In addition, the definition of the Polya number involves measurement of the system. Depending on how measurement is included in the definition, the recurrence properties vary. We show that in the limiting case of frequent, strong measurements, one can approach the classical dynamics. Comparing various cases, we have found numerical indication that our previous definition of the Polya number provides an upper limit.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article; Proceedings Paper}}, language = {{English}}, affiliation = {{Kiss, T (Reprint Author), Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Konkoly Thege M U 29-33, H-1121 Budapest, Hungary. Kiss, T.; Kecskes, L., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, H-1121 Budapest, Hungary. Stefanak, M.; Jex, I., FJFI CVUT Praze, Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic.}}, doi = {{10.1088/0031-8949/2009/T135/014055}}, article-number = {{014055}}, issn = {{0031-8949}}, keywords-plus = {{CELLULAR-AUTOMATA}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{tkiss@szfki.hu}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012}}, number-of-cited-references = {{16}}, times-cited = {{4}}, journal-iso = {{Phys. Scr.}}, doc-delivery-number = {{493WB}}, unique-id = {{ISI:000269768300057}} }
@article{ISI:000265678400027, author = {Stefanak, M. and Kiss, T. and Jex, I.}, title = {{Recurrence of biased quantum walks on a line}}, journal = {{NEW JOURNAL OF PHYSICS}}, year = {{2009}}, volume = {{11}}, month = {{APR}}, abstract = {{The Polya number of a classical random walk on a regular lattice is known to depend solely on the dimension of the lattice. For one and two dimensions it equals one, meaning unit probability of returning to the origin. This result is extremely sensitive to the directional symmetry, and any deviation from the equal probability of travelling in each direction results in a change of the character of the walk from recurrent to transient. Applying our definition of the Polya number to quantum walks on a line we show that the recurrence character of quantum walks is more stable against bias. We determine the range of parameters for which biased quantum walks remain recurrent. We find that there exist genuine biased quantum walks that are recurrent.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Stefanak, M.; Jex, I., Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic. Kiss, T., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Dept Nonlinear \& Quantum Opt, H-1121 Budapest, Hungary.}}, doi = {{10.1088/1367-2630/11/4/043027}}, article-number = {{043027}}, issn = {{1367-2630}}, keywords-plus = {{ONE-DIMENSION}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{martin.stefanak@fjfi.cvut.cz}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012}}, number-of-cited-references = {{35}}, times-cited = {{19}}, journal-iso = {{New J. Phys.}}, doc-delivery-number = {{440DD}}, unique-id = {{ISI:000265678400027}} }
@article{ISI:000263815000146, author = {Hamilton, Craig S. and Lavicka, Hynek and Andersson, Erika and Jeffers, John and Jex, Igor}, title = {{Quantum public key distribution with imperfect device components}}, journal = {{PHYSICAL REVIEW A}}, year = {{2009}}, volume = {{79}}, number = {{2}}, month = {{FEB}}, abstract = {{We examine the operation of a device for a public quantum key distribution network. The recipients attempt to determine whether or not their individual key copies, which are a sequence of coherent states, are identical. To quantify the success of the protocol we use a fidelity-based figure of merit and describe a method for increasing this in the presence of noise and imperfect detectors. We show that the fidelity may be written as the product of two factors: one that depends on the properties of the device setup and another that depends on the detectors used. We then demonstrate the effect various parameters have on the overall effective operation of the device.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Hamilton, CS (Reprint Author), Univ Strathclyde, Dept Phys, SUPA, Computat Nonlinear \& Quantum Opt Grp, John Anderson Bldg,107 Rottenrow, Glasgow G4 0NG, Lanark, Scotland. Hamilton, Craig S.; Andersson, Erika; Jeffers, John, Univ Strathclyde, Dept Phys, SUPA, Computat Nonlinear \& Quantum Opt Grp, Glasgow G4 0NG, Lanark, Scotland. Lavicka, Hynek; Jex, Igor, Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic. Andersson, Erika, Heriot Watt Univ, Sch Engn \& Phys Sci, SUPA, Edinburgh EH14 4AS, Midlothian, Scotland.}}, doi = {{10.1103/PhysRevA.79.023808}}, article-number = {{023808}}, issn = {{1050-2947}}, eissn = {{1094-1622}}, keywords = {{cryptographic protocols; quantum cryptography}}, keywords-plus = {{STATES; CRYPTOGRAPHY; COHERENT; OPTICS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Jeffers, John/A-1738-2009 Andersson, Erika/D-1139-2013}}, orcid-numbers = {{Jeffers, John/0000-0002-8573-1675 Andersson, Erika/0000-0001-5856-6806}}, funding-acknowledgement = {{Royal Society International Joint Project scheme; Royal Society Dorothy Hodgkin; EPSRC; {[}MSM 68407739]; {[}MSMT LC 06002]}}, funding-text = {{All authors gratefully acknowledge support from Czech Grants No. MSM 68407739 and No. MSMT LC 06002 and the Royal Society International Joint Project scheme. E. A. also gratefully acknowledges support from the Royal Society Dorothy Hodgkin scheme. C. S. H. acknowledges financial support from EPSRC.}}, number-of-cited-references = {{27}}, times-cited = {{7}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{413TI}}, unique-id = {{ISI:000263815000146}} }
@article{ISI:000270173800007, author = {Brougham, Thomas and Chadzitaskos, Goce and Jex, Igor}, title = {{Transformation design and nonlinear Hamiltonians}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{2009}}, volume = {{56}}, number = {{14}}, pages = {{1588-1597}}, abstract = {{We study a class of nonlinear Hamiltonians, with applications in quantum optics. The interaction terms of these Hamiltonians are generated by taking a linear combination of powers of a simple `beam splitter' Hamiltonian. The entanglement properties of the eigenstates are studied. Finally, we show how to use this class of Hamiltonians to perform special tasks such as conditional state swapping, which can be used to generate optical cat states and to sort photons.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Brougham, T (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague 1, Czech Republic. Brougham, Thomas; Chadzitaskos, Goce; Jex, Igor, Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague 1, Czech Republic.}}, doi = {{10.1080/09500340903194633}}, issn = {{0950-0340}}, keywords = {{quantum optics; nonlinear optics; quantum information}}, keywords-plus = {{LOSSLESS BEAM SPLITTER; ORTHOGONAL POLYNOMIALS; SU(2) SYMMETRY; QUANTUM; SYSTEMS; STATISTICS; MECHANICS; STATES}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, author-email = {{thomas.brougham@gmail.com}}, funding-acknowledgement = {{Czech Republic {[}MSM-6840770039, MSMT LC06002]}}, funding-text = {{We acknowledge financial support from Grants MSM-6840770039 and MSMT LC06002 of the Czech Republic. The authors are obliged to Professor A. Odzijewicz for helpful comments and remarks.}}, number-of-cited-references = {{23}}, times-cited = {{1}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{498VR}}, unique-id = {{ISI:000270173800007}} }
@article{ISI:000262979000060, author = {Potocek, V. and Gabris, A. and Kiss, T. and Jex, I.}, title = {{Optimized quantum random-walk search algorithms on the hypercubel}}, journal = {{PHYSICAL REVIEW A}}, year = {{2009}}, volume = {{79}}, number = {{1}}, month = {{JAN}}, abstract = {{Shenvi, Kempe, and Whaley's quantum random-walk search (SKW) algorithm {[}Phys. Rev. A 67, 052307 (2003)] is known to require O(root N) number of oracle queries to find the marked element, where N is the size of the search space. The overall time complexity of the SKW algorithm differs from the best achievable on a quantum computer only by a constant factor. We present improvements to the SKW algorithm which yield a significant increase in success probability, and an improvement on query complexity such that the theoretical limit of a search algorithm succeeding with probability close to one is reached. We point out which improvement can be applied if there is more than one marked element to find.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Potocek, V (Reprint Author), Czech Tech Univ, FJFI,Dept Phys, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Potocek, V.; Gabris, A.; Jex, I., Czech Tech Univ, FJFI,Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic. Gabris, A.; Kiss, T., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, H-1525 Budapest, Hungary.}}, doi = {{10.1103/PhysRevA.79.012325}}, article-number = {{012325}}, issn = {{1050-2947}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Gabris, Aurel/A-7615-2008}}, number-of-cited-references = {{16}}, times-cited = {{28}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{401YE}}, unique-id = {{ISI:000262979000060}} }
@article{ISI:000259689400036, author = {Stefanak, M. and Kiss, T. and Jex, I.}, title = {{Recurrence properties of unbiased coined quantum walks on infinite d-dimensional lattices}}, journal = {{PHYSICAL REVIEW A}}, year = {{2008}}, volume = {{78}}, number = {{3}}, month = {{SEP}}, abstract = {{The Polya number characterizes the recurrence of a random walk. We apply the generalization of this concept to quantum walks {[}M. Stefanak et al., Phys. Rev. Lett. 100, 020501 (2008)] which is based on a specific measurement scheme. The Polya number of a quantum walk depends, in general, on the choice of the coin and the initial coin state, in contrast to classical random walks where the lattice dimension uniquely determines it. We analyze several examples to depict the variety of possible recurrence properties. First, we show that for the class of quantum walks driven by Hadamard tensor-product coins, the Polya number is independent of the initial conditions and the actual coin operators, thus resembling the property of the classical walks. We provide an estimation of the Polya number for this class of quantum walks. Second, we examine the two-dimensional Grover walk, which exhibits localization and thus is recurrent, except for a particular initial state for which the walk is transient. We generalize the Grover walk to show that one can construct in arbitrary dimensions a quantum walk which is recurrent. This is in great contrast with classical walks which are recurrent only for the dimensions d=1,2. Finally, we analyze the recurrence of the 2D Fourier walk. This quantum walk is recurrent except for a two-dimensional subspace of the initial states. We provide an estimation of the Polya number in its dependence on the initial state.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, FJFI,Dept Phys, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Stefanak, M.; Jex, I., Czech Tech Univ, FJFI,Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic. Kiss, T., Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Dept Nonlinear \& Quantum Opt, H-1121 Budapest, Hungary.}}, doi = {{10.1103/PhysRevA.78.032306}}, article-number = {{032306}}, issn = {{1050-2947}}, keywords-plus = {{CELLULAR-AUTOMATA; SCATTERING-THEORY; LIMIT-THEOREMS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012}}, number-of-cited-references = {{59}}, times-cited = {{36}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{355DO}}, unique-id = {{ISI:000259689400036}} }
@article{ISI:000258398400020, author = {Kiss, T. and Jex, I. and Alber, G. and Kollar, E.}, title = {{Properties of complex chaos in conditional qubit dynamics}}, journal = {{INTERNATIONAL JOURNAL OF QUANTUM INFORMATION}}, year = {{2008}}, volume = {{6}}, number = {{1}}, pages = {{695-700}}, month = {{JUL}}, note = {{International Meeting on Noise, Information and Complexity AT Quantum Scale, Erice, ITALY, NOV 02-10, 2007}}, abstract = {{Complex chaos is specified by an iterated mapping on complex numbers. It has recently been found in the dynamics of qubits where each time step is conditioned on a measurement result on part of the system. We analyse the simplest case of one qubit dynamics with one complex parameter in some detail. We point out that two attractive cycles can exist and provide examples how the fractal like Julia set divides the areas of corresponding initial states. We show how to determine the set of parameters for which one, two or no stable fixed cycles exists and provide the numerically calculated images of the sets. The results can be relevant for the quantum state purification protocol based on the similar dynamics of two or more qubits and in general for any protocol based on conditioned nonlinear dynamics where truly chaotic behavior may occur.}}, publisher = {{WORLD SCIENTIFIC PUBL CO PTE LTD}}, address = {{5 TOH TUCK LINK, SINGAPORE 596224, SINGAPORE}}, type = {{Article; Proceedings Paper}}, language = {{English}}, affiliation = {{Kiss, T (Reprint Author), Res Inst Solid State Phys \& Opt, POB 49, H-1525 Budapest, Hungary. Kiss, T., Res Inst Solid State Phys \& Opt, H-1525 Budapest, Hungary. Jex, I., Czech Tech Univ, FJFI,Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic. Alber, G., Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany. Kollar, E., Eotvos Lorand Univ, H-1117 Budapest, Hungary.}}, doi = {{10.1142/S0219749908003979}}, issn = {{0219-7499}}, keywords = {{quantum chaos; complex chaos; purification}}, research-areas = {{Computer Science; Physics}}, web-of-science-categories = {{Computer Science, Theory \& Methods; Physics, Particles \& Fields; Physics, Mathematical}}, author-email = {{tkiss@szfki.hu}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009}}, number-of-cited-references = {{12}}, times-cited = {{2}}, journal-iso = {{Int. J. Quantum Inf.}}, doc-delivery-number = {{336XG}}, unique-id = {{ISI:000258398400020}} }
@article{ISI:000252476500021, author = {Geberth, D. and Kern, O. and Alber, G. and Jex, I.}, title = {{Stabilization of quantum information by combined dynamical decoupling and detected-jump error correction}}, journal = {{EUROPEAN PHYSICAL JOURNAL D}}, year = {{2008}}, volume = {{46}}, number = {{2}}, pages = {{381-394}}, month = {{FEB}}, abstract = {{Two possible applications of random decoupling are discussed. Whereas so far decoupling methods have been considered merely for quantum memories, here it is demonstrated that random decoupling is also a convenient tool for stabilizing quantum algorithms. Furthermore, a decoupling scheme is presented which involves a random decoupling method compatible with detected-jump error correcting quantum codes. With this combined error correcting strategy it is possible to stabilize quantum information against both spontaneous decay and static imperfections of a qubit-based quantum information processor in an efficient way.}}, publisher = {{SPRINGER}}, address = {{233 SPRING ST, NEW YORK, NY 10013 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Geberth, D (Reprint Author), Tech Univ Darmstadt, Inst Angew Phys, Petersenstr 30, D-64289 Darmstadt, Germany. Geberth, D.; Kern, O.; Alber, G., Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany. Jex, I., Czech Tech Univ, FJFI, Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic.}}, doi = {{10.1140/epjd/e2007-00303-6}}, issn = {{1434-6060}}, keywords-plus = {{SIMULATION; FIDELITY; CODES; DECAY; CHAOS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{oliver.kern@physik.tu-darmstadt.de}}, number-of-cited-references = {{23}}, times-cited = {{0}}, journal-iso = {{Eur. Phys. J. D}}, doc-delivery-number = {{252WC}}, unique-id = {{ISI:000252476500021}} }
@article{ISI:000252471200003, author = {Stefanak, M. and Jex, I. and Kiss, T.}, title = {{Recurrence and polya number of quantum walks}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{2008}}, volume = {{100}}, number = {{2}}, month = {{JAN 18}}, abstract = {{We analyze the recurrence probability (Polya number) for d-dimensional unbiased quantum walks. A sufficient condition for a quantum walk to be recurrent is derived. As a by-product we find a simple criterion for localization of quantum walks. In contrast with classical walks, where the Polya number is characteristic for the given dimension, the recurrence probability of a quantum walk depends in general on the topology of the walk, choice of the coin and the initial state. This allows us to change the character of the quantum walk from recurrent to transient by altering the initial state.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, FJFI, Dept Phys, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Stefanak, M.; Jex, I., Czech Tech Univ, FJFI, Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic. Stefanak, M., Univ Ulm, Inst Quantum Phys, D-89069 Ulm, Germany. Kiss, T., Hungarian Acad Sci, Res Inst Solid State Phys Opt, Dept Nonlinear \& Quantum Opt, H-1121 Budapest, Hungary.}}, doi = {{10.1103/PhysRevLett.100.020501}}, article-number = {{020501}}, issn = {{0031-9007}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012}}, number-of-cited-references = {{22}}, times-cited = {{41}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{252UD}}, unique-id = {{ISI:000252471200003}} }
@inproceedings{ISI:000263640400034, author = {Vymetal, S. and Kiss, T. and Jex, I. and Alber, G. and Gabris, A. and Langrova, T.}, editor = {{Robnik, M and Romanovski, VG}}, title = {{Chaos in the conditional dynamics of two qubits purification protocol}}, booktitle = {{LET'S FACE CHAOS THROUGH NONLINEAR DYNAMICS}}, series = {{AIP Conference Proceedings}}, year = {{2008}}, volume = {{1076}}, pages = {{255-261}}, note = {{7th International Summer School and Conference on Lets Face Chaos through Nonlinear Dynamics, Univ Maribor, Maribor, SLOVENIA, JUN 29-JUL 13, 2008}}, organization = {{Slovenian Res Agcy; GEN Energija; Telekom Slovenije; Nova KBM}}, abstract = {{The presence of complex chaos in iterative apphcations of selective dynamics on quantum systems is a novel form of quantum chaos with true sensitivity to initial conditions. Techniques for the study of pure states are extended to the two-qubit case(1).}}, publisher = {{AMER INST PHYSICS}}, address = {{2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{Vymetal, S (Reprint Author), FJFI CVUT, Dept Phys, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Vymetal, S.; Jex, I.; Gabris, A.; Langrova, T., FJFI CVUT, Dept Phys, Prague 11519 1, Stare Mesto, Czech Republic.}}, issn = {{0094-243X}}, isbn = {{978-0-7354-0607-0}}, keywords = {{complex chaos; quantum chaos; purification protocol}}, research-areas = {{Mathematics; Physics}}, web-of-science-categories = {{Mathematics, Applied; Physics, Mathematical}}, author-email = {{stanislav.vymetal@gmail.com}}, researcherid-numbers = {{Gabris, Aurel/A-7615-2008}}, number-of-cited-references = {{7}}, times-cited = {{0}}, doc-delivery-number = {{BIX85}}, unique-id = {{ISI:000263640400034}} }
@article{ISI:000251985900037, author = {Gabris, A. and Kiss, T. and Jex, I.}, title = {{Scattering quantum random-walk search with errors}}, journal = {{PHYSICAL REVIEW A}}, year = {{2007}}, volume = {{76}}, number = {{6}}, month = {{DEC}}, abstract = {{We analyze the realization of a quantum-walk search algorithm in a passive, linear optical network. The specific model enables us to consider the effect of realistic sources of noise and losses on the search efficiency. Photon loss uniform in all directions is shown to lead to the rescaling of search time. Deviation from directional uniformity leads to the enhancement of the search efficiency compared to uniform loss with the same average. In certain cases even increasing loss in some of the directions can improve search efficiency. We show that while we approach the classical limit of the general search algorithm by introducing random phase fluctuations, its utility for searching is lost. Using numerical methods, we found that for static phase errors the averaged search efficiency displays a damped oscillatory behavior that asymptotically tends to a nonzero value.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Gabris, A (Reprint Author), Res Inst Solid State Phys \& Opt, POB 49, H-1525 Budapest, Hungary. Gabris, A.; Kiss, T., Res Inst Solid State Phys \& Opt, H-1525 Budapest, Hungary. Jex, I., Czech Tech Univ, FJFI, Dept Phys, Prague 11519, Czech Republic.}}, doi = {{10.1103/PhysRevA.76.062315}}, article-number = {{062315}}, issn = {{1050-2947}}, keywords-plus = {{MULTIPORT}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Gabris, Aurel/A-7615-2008 Kiss, Tamas/B-9228-2009}}, number-of-cited-references = {{31}}, times-cited = {{12}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{246CU}}, unique-id = {{ISI:000251985900037}} }
@article{ISI:000247624300191, author = {Tereszkiewicz, Agnieszka and Odzijewicz, Anatol and Horowski, Maciej and Jex, Igor and Chadzitaskos, Goce}, title = {{Explicitly solvable models of a two-mode coupler in Kerr media}}, journal = {{PHYSICAL REVIEW A}}, year = {{2007}}, volume = {{75}}, number = {{6}}, month = {{JUN}}, abstract = {{We present exact solutions for two nonlinear models each of which describes parametric down conversion of photons as well as the Kerr effect. The Hamiltonians for these models are related to the dual Hahn finite orthogonal polynomials. Explicit expressions are obtained for the spectra and for the eigenvectors of the Hamiltonians. A discussion of the physical characteristics of the systems is presented.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Tereszkiewicz, A (Reprint Author), Univ Bialystok, Inst Math, Lipowa 41, PL-15424 Bialystok, Poland. Univ Bialystok, Inst Math, PL-15424 Bialystok, Poland. Czech Tech Univ, Dept Phys, CR-11519 Prague, Czech Republic.}}, doi = {{10.1103/PhysRevA.75.063817}}, article-number = {{063817}}, issn = {{1050-2947}}, keywords-plus = {{NONLINEAR QUANTUM OPTICS; ORTHOGONAL POLYNOMIALS; PERIODIC DECAY; STATES; CONVERSION; REVIVAL; SYSTEMS; ALGEBRAS; ATOM}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{tereszk@uwb.edu.pl aodzijew@uwb.edu.pl horowski@alpha.uwb.edu.pl igor.jex@fjfi.cvut.cz goce.chadzitaskos@fjfi.cvut.cz}}, number-of-cited-references = {{29}}, times-cited = {{1}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{184EQ}}, unique-id = {{ISI:000247624300191}} }
@article{ISI:000246890400037, author = {Probst-Schendzielorz, Stefan T. and Wolf, Alexander and Freyberger, Matthias and Jex, Igor and He, Bing and Bergou, Janos A.}, title = {{Unambiguous discriminator for unknown quantum states: An implementation}}, journal = {{PHYSICAL REVIEW A}}, year = {{2007}}, volume = {{75}}, number = {{5}}, month = {{MAY}}, abstract = {{We give a scheme for a physical implementation of the programmable state discriminator that unambiguously discriminates between two unknown qubit states with optimal probability of success. One copy of each of the unknown states is provided as input, or program, for the two program registers, and the data state, which is guaranteed to be prepared in one of the program states, is fed into the data register of the device. This device will then tell us, in an optimal way, which of the templates stored in the program registers the data state matches. The implementation is based on Neumark's theorem. We introduce a single qubit as ancilla and a unitary operator that entangles the system with the ancilla in such a way that projective measurements performed in the computational basis of the system plus ancilla transform the initial system states according to the optimal positive-operator-valued measure.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Probst-Schendzielorz, ST (Reprint Author), Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Czech Tech Univ Prague, Dept Phys, FNSPE, Prague 11519, Czech Republic. CUNY Hunter Coll, Dept Phys \& Astron, Beijing 100021, Peoples R China.}}, doi = {{10.1103/PhysRevA.75.052116}}, article-number = {{052116}}, issn = {{1050-2947}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, author-email = {{Stefan.Probst@uni-ulm.de}}, number-of-cited-references = {{15}}, times-cited = {{10}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{173RO}}, unique-id = {{ISI:000246890400037}} }
@article{ISI:000246074600044, author = {Kostak, V. and Nikolopoulos, G. M. and Jex, I.}, title = {{Perfect state transfer in networks of arbitrary topology and coupling configuration}}, journal = {{PHYSICAL REVIEW A}}, year = {{2007}}, volume = {{75}}, number = {{4}}, month = {{APR}}, abstract = {{A general formalism of the problem of perfect state transfer is presented. We show that there are infinitely many Hamiltonians that may provide a solution to this problem. In a first attempt to give a classification of them we investigate their possible forms and the related dynamics during the transfer. Finally, we show how the present formalism can be used for the engineering of perfect quantum wires of various topologies and coupling configurations.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Kostak, V (Reprint Author), Czech Tech Univ, Dept Phys, FJFI, Brehova 7, Prague 11519 1, Czech Republic. Czech Tech Univ, Dept Phys, FJFI, Prague 11519 1, Czech Republic. Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany.}}, doi = {{10.1103/PhysRevA.75.042319}}, article-number = {{042319}}, issn = {{1050-2947}}, keywords-plus = {{N-LEVEL ATOMS; ELECTRON WAVEPACKET PROPAGATION; COHERENT DYNAMICS; ENTANGLEMENT GENERATION; QUANTUM DOTS; MOLECULES}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Nikolopoulos, Georgios/H-3023-2011}}, orcid-numbers = {{Nikolopoulos, Georgios/0000-0002-3937-2771}}, number-of-cited-references = {{27}}, times-cited = {{33}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{162GJ}}, unique-id = {{ISI:000246074600044}} }
@article{ISI:000246074600034, author = {Novotny, J. and Alber, G. and Jex, I.}, title = {{Network implementation of covariant two-qubit quantum operations}}, journal = {{PHYSICAL REVIEW A}}, year = {{2007}}, volume = {{75}}, number = {{4}}, month = {{APR}}, abstract = {{A six-qubit quantum network consisting of conditional unitary gates is presented which is capable of implementing a large class of covariant two-qubit quantum operations. Optimal covariant NOT operations for one- and two-qubit systems are special cases contained in this class. The design of this quantum network exploits basic algebraic properties which also shed light onto these covariant quantum processes.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Czech Tech Univ, Dept Phys, FJFI, Brehova 7, Prague 11519 1, Czech Republic. Czech Tech Univ, Dept Phys, FJFI, Prague 11519 1, Czech Republic. Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany.}}, doi = {{10.1103/PhysRevA.75.042309}}, article-number = {{042309}}, issn = {{1050-2947}}, keywords-plus = {{OPTIMAL CLONING; PURE STATES}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{14}}, times-cited = {{0}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{162GJ}}, unique-id = {{ISI:000246074600034}} }
@article{ISI:000242406200010, author = {Stefanak, M. and Kiss, T. and Jex, I. and Mohring, B.}, title = {{The meeting problem in the quantum walk}}, journal = {{JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL}}, year = {{2006}}, volume = {{39}}, number = {{48}}, pages = {{14965-14983}}, month = {{DEC 1}}, abstract = {{We study the motion of two non-interacting quantum particles performing a random walk on a line and analyse the probability that the two particles are detected at a particular position after a certain number of steps (meeting problem). The results are compared to the corresponding classical problem and differences are pointed out. Analytic formulae for the meeting probability and its asymptotic behaviour are derived. The decay of the meeting probability for distinguishable particles is faster than in the classical case, but not quadratically. Entangled initial states and the bosonic or fermionic nature of the walkers are considered.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Stefanak, M (Reprint Author), Czech Tech Univ, Dept Phys, FJFI, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Czech Tech Univ, Dept Phys, FJFI, Prague 11519 1, Stare Mesto, Czech Republic. Hungarian Acad Sci, Res Inst Solid State Phys \& Opt, Dept Nonlinear \& Quantum Opt, H-1121 Budapest, Hungary. Univ Ulm, Inst Quantum Phys, D-89069 Ulm, Germany.}}, doi = {{10.1088/0305-4470/39/48/009}}, issn = {{0305-4470}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary; Physics, Mathematical}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012}}, number-of-cited-references = {{27}}, times-cited = {{8}}, journal-iso = {{J. Phys. A-Math. Gen.}}, doc-delivery-number = {{110UG}}, unique-id = {{ISI:000242406200010}} }
@article{ISI:000241723100001, author = {Kiss, T. and Jex, I. and Alber, G. and Vymetal, S.}, title = {{Complex chaos in the conditional dynamics of qubits}}, journal = {{PHYSICAL REVIEW A}}, year = {{2006}}, volume = {{74}}, number = {{4}}, month = {{OCT}}, abstract = {{We analyze the consequences of iterative measurement-induced nonlinearity on the dynamical behavior of qubits. We present a one-qubit scheme where the equation governing the time evolution is a complex-valued nonlinear map with one complex parameter. In contrast to the usual notion of quantum chaos, exponential sensitivity to the initial state occurs here. We calculate analytically the Lyapunov exponent based on the overlap of quantum states, and find that it is positive. We present a few illustrative examples of the emerging dynamics.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Kiss, T (Reprint Author), Res Inst Solid State Phys \& Opt, POB 49, H-1525 Budapest, Hungary. Res Inst Solid State Phys \& Opt, H-1525 Budapest, Hungary. Czech Tech Univ, Dept Phys, FJFI, Prague 11519 1, Czech Republic. Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany.}}, doi = {{10.1103/PhysRevA.74.040301}}, article-number = {{040301}}, issn = {{1050-2947}}, keywords-plus = {{EXPONENTIAL SENSITIVITY; QUANTUM-SYSTEMS; LOCALIZATION}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009}}, number-of-cited-references = {{25}}, times-cited = {{9}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{101EX}}, unique-id = {{ISI:000241723100001}} }
@article{ISI:000240238300021, author = {Andersson, Erika and Curty, Marcos and Jex, Igor}, title = {{Experimentally realizable quantum comparison of coherent states and its applications}}, journal = {{PHYSICAL REVIEW A}}, year = {{2006}}, volume = {{74}}, number = {{2}}, month = {{AUG}}, abstract = {{When comparing quantum states to each other, it is possible to obtain an unambiguous answer, indicating that the states are definitely different, already after a single measurement. In this paper we investigate comparison of coherent states, which is the simplest example of quantum state comparison for continuous variables. The method we present has a high success probability, and is experimentally feasible to realize as the only required components are beam splitters and photon detectors. An easily realizable method for quantum state comparison could be important for real applications. As examples of such applications we present a ``lock and key{''} scheme and a simple scheme for quantum public key distribution.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Andersson, E (Reprint Author), Univ Strathclyde, Dept Phys, SUPA, Glasgow G4 0NG, Lanark, Scotland. Univ Strathclyde, Dept Phys, SUPA, Glasgow G4 0NG, Lanark, Scotland. Univ Erlangen Nurnberg, Inst Theoret Phys 1, Quantum Informat Theory Grp, D-91058 Erlangen, Germany. Univ Erlangen Nurnberg, Inst Opt Informat \& Photon, Max Planck Res Grp, D-91058 Erlangen, Germany. Czech Tech Univ, Dept Phys, FNSPE, Prague 1, Czech Republic.}}, doi = {{10.1103/PhysRevA.74.022304}}, article-number = {{022304}}, issn = {{1050-2947}}, keywords-plus = {{SYSTEMS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Andersson, Erika/D-1139-2013 Curty, Marcos/L-2416-2014}}, orcid-numbers = {{Andersson, Erika/0000-0001-5856-6806 Curty, Marcos/0000-0002-0330-6828}}, number-of-cited-references = {{25}}, times-cited = {{39}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{080HK}}, unique-id = {{ISI:000240238300021}} }
@article{ISI:000238694900044, author = {Novotny, J. and Alber, G. and Jex, I.}, title = {{Completely positive covariant two-qubit quantum processes and optimal quantum NOT operations for entangled qubit pairs}}, journal = {{PHYSICAL REVIEW A}}, year = {{2006}}, volume = {{73}}, number = {{6}}, month = {{JUN}}, abstract = {{The structure is investigated of all completely positive quantum operations that transform pure two-qubit input states of a given degree of entanglement in a covariant way. Special cases thereof are quantum NOT operations which transform entangled pure two-qubit input states of a given degree of entanglement into orthogonal states in an optimal way. Based on our general analysis all covariant optimal two-qubit quantum NOT operations are determined. In particular, it is demonstrated that only in the case of maximally entangled input states can these quantum NOT operations be performed perfectly.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Czech Tech Univ, Dept Phys, FJFI, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Czech Tech Univ, Dept Phys, FJFI, Prague 11519 1, Stare Mesto, Czech Republic. Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany.}}, doi = {{10.1103/PhysRevA.73.062311}}, article-number = {{062311}}, issn = {{1050-2947}}, keywords-plus = {{OPTIMAL CLONING; PURE STATES; MAPS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{20}}, times-cited = {{3}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{058WI}}, unique-id = {{ISI:000238694900044}} }
@article{ISI:000233112500019, author = {Novotny, J and Stefanak, M and Kiss, T and Jex, I}, title = {{Control of entanglement in Ising-type networks with one and two excitations}}, journal = {{JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL}}, year = {{2005}}, volume = {{38}}, number = {{41}}, pages = {{9087-9103}}, month = {{OCT 14}}, abstract = {{We analyse the dynamics of single- and two-particle states in Ising-type networks. The mutual entanglement is quantified using the concept of concurrence. We derive explicit expressions for the concurrence for single and two-particle initial states in arbitrary passive networks and specify the result for Ising-type networks. We show how to design a network to prepare a prescribed pattern of entanglement for one excitation and study the maximum attainable entanglement for passive optical networks in general. The effect of network randomization on the average entanglement is also studied.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Czech Tech Univ, Dept Phys, FJFI, Brehova 7, CS-11519 Prague 1, Czech Republic. Czech Tech Univ, Dept Phys, FJFI, CS-11519 Prague 1, Czech Republic. Hungarian Acad Sci, Dept Nonlinear \& Quantum Opt, Res Inst Solid State Phys \& Opt, H-1121 Budapest, Hungary.}}, doi = {{10.1088/0305-4470/38/41/017}}, issn = {{0305-4470}}, keywords-plus = {{INTERACTING PARTICLES; STATES}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary; Physics, Mathematical}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Stefanak, Martin/G-5239-2012}}, number-of-cited-references = {{18}}, times-cited = {{4}}, journal-iso = {{J. Phys. A-Math. Gen.}}, doc-delivery-number = {{981UC}}, unique-id = {{ISI:000233112500019}} }
@article{ISI:000230108100011, author = {Andersson, E and Bergou, J and Jex, I}, title = {{Comparison of unitary transforms using Franson interferometry}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{2005}}, volume = {{52}}, number = {{10}}, pages = {{1485-1494}}, month = {{JUL 10}}, abstract = {{Unknown unitary transforms may be compared to each other in a way which makes it possible to obtain an unambiguous answer, indicating that the transforms are different, already after a single application of each transform. Quantum comparison strategies may be useful for example if we want to test the performance of individual gates in a quantum information or quantum computing network. It is then possible to check for errors by comparing the elements to a master copy of the gate, instead of performing a complete tomography of the gate. In this paper we propose a versatile linear optical implementation based on the Franson interferometer with short and long arms. A click in the wrong output port unambiguously determines that the tested gate is faulty. This set-up can also be used for a variety of other tasks, such as confirming that the two transforms do not commute or do not anticommute.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Andersson, E (Reprint Author), Univ Strathclyde, Dept Phys, Glasgow G4 0NG, Lanark, Scotland. Univ Strathclyde, Dept Phys, Glasgow G4 0NG, Lanark, Scotland. CUNY Hunter Coll, Dept Phys \& Astron, New York, NY 10021 USA. Czech Tech Univ Prague, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic.}}, doi = {{10.1080/09500340500052911}}, issn = {{0950-0340}}, keywords-plus = {{QUANTUM-SYSTEMS; STATES; TIME}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, author-email = {{erika@phys.strath.ac.uk}}, researcherid-numbers = {{Andersson, Erika/D-1139-2013}}, orcid-numbers = {{Andersson, Erika/0000-0001-5856-6806}}, number-of-cited-references = {{10}}, times-cited = {{2}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{939YG}}, unique-id = {{ISI:000230108100011}} }
@article{ISI:000228752700052, author = {Novotny, J and Alber, G and Jex, I}, title = {{Optimal copying of entangled two-qubit states}}, journal = {{PHYSICAL REVIEW A}}, year = {{2005}}, volume = {{71}}, number = {{4}}, month = {{APR}}, abstract = {{We investigate the problem of copying pure two-qubit states of a given degree of entanglement in an optimal way. Completely positive covariant quantum operations are constructed which maximize the fidelity of the output states with respect to two separable copies. These optimal copying processes hint at the intricate relationship between fundamental laws of quantum theory and entanglement.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Novotny, J (Reprint Author), Czech Tech Univ, Dept Phys, FJFI, Brehova 7, Prague 11519 1, Stare Mesto, Czech Republic. Czech Tech Univ, Dept Phys, FJFI, Prague 11519 1, Stare Mesto, Czech Republic. Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany.}}, doi = {{10.1103/PhysRevA.71.042332}}, article-number = {{042332}}, issn = {{1050-2947}}, keywords-plus = {{OPTIMAL CLONING; QUANTUM BIT; QUBITS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{24}}, times-cited = {{7}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{921GR}}, unique-id = {{ISI:000228752700052}} }
@article{ISI:000223254200013, author = {Chefles, A and Andersson, E and Jex, I}, title = {{Unambiguous comparison of the states of multiple quantum systems}}, journal = {{JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL}}, year = {{2004}}, volume = {{37}}, number = {{29}}, pages = {{7315-7340}}, month = {{JUL 23}}, abstract = {{We consider N quantum systems initially prepared in pure states and address the problem of unambiguously comparing them. One may ask whether or not all N systems are in the same state. Alternatively, one may ask whether or not the states of all N systems are different. We investigate the possibility of unambiguously obtaining this kind of information. It is found that some unambiguous comparison tasks are possible only when certain linear independence conditions are satisfied. We also obtain measurement strategies for certain comparison tasks which are optimal under a broad range of circumstances, in particular when the states are completely unknown. Such strategies, which we call universal comparison strategies, are found to have intriguing connections with the problem of quantifying the distinguishability of a set of quantum states and also with unresolved conjectures in linear algebra. We finally investigate a potential generalization of unambiguous state comparison, which we term unambiguous overlap filtering.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Chefles, A (Reprint Author), Univ Hertfordshire, Sch Phys Astron \& Math, Hatfield AL10 9AB, Herts, England. Univ Hertfordshire, Sch Phys Astron \& Math, Hatfield AL10 9AB, Herts, England. Univ Strathclyde, Dept Phys, Glasgow G4 0NG, Lanark, Scotland. Czech Tech Univ, FNSPE, Dept Phys, Prague 11519, Czech Republic.}}, doi = {{10.1088/0305-4470/37/29/009}}, issn = {{0305-4470}}, keywords-plus = {{DISCRIMINATION; DETERMINANT; PERMANENT}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary; Physics, Mathematical}}, researcherid-numbers = {{Andersson, Erika/D-1139-2013}}, orcid-numbers = {{Andersson, Erika/0000-0001-5856-6806}}, number-of-cited-references = {{34}}, times-cited = {{20}}, journal-iso = {{J. Phys. A-Math. Gen.}}, doc-delivery-number = {{845OM}}, unique-id = {{ISI:000223254200013}} }
@article{ISI:000187993900004, author = {Jex, I and Andersson, E and Chefles, A}, title = {{Comparing the states of many quantum systems}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{2004}}, volume = {{51}}, number = {{4}}, pages = {{505-523}}, month = {{MAR 10}}, abstract = {{We investigate how to determine whether the states of a set of quantum systems are identical or not. This paper treats both error-free comparison, and comparison where errors in the result are allowed. Error-free comparison means that we aim to obtain definite answers, which are known to be correct, as often as possible. In general, we will also have to accept inconclusive results, giving no information. To obtain a definite answer that the states of the systems are not identical is always possible, whereas in the situation considered here, a definite answer that they are identical will not be possible. The optimal universal error-free comparison strategy is a projection onto the totally symmetric and the different non-symmetric subspaces, invariant under permutations and unitary transformations. We also show how to construct optimal comparison strategies when allowing for some errors in the result, minimizing either the error probability, or the average cost of making an error. We point out that it is possible to realize universal error-free comparison strategies using only linear elements and particle detectors, albeit with less than ideal efficiency. Also minimum-error and minimum-cost strategies may sometimes be realized in this way. This is of great significance for practical applications of quantum comparison.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Jex, I (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague, Czech Republic. Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic. Univ Hertfordshire, Dept Phys Sci, Hatfield AL10 9AB, Herts, England. Univ Strathclyde, Dept Phys, Glasgow G4 0NG, Lanark, Scotland.}}, doi = {{10.1080/09500340310001620475}}, issn = {{0950-0340}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Andersson, Erika/D-1139-2013}}, orcid-numbers = {{Andersson, Erika/0000-0001-5856-6806}}, number-of-cited-references = {{23}}, times-cited = {{16}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{762QP}}, unique-id = {{ISI:000187993900004}} }
@article{ISI:000181878900011, author = {Andersson, E and Jex, I and Barnett, SM}, title = {{Comparison of unitary transforms}}, journal = {{JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL}}, year = {{2003}}, volume = {{36}}, number = {{9}}, pages = {{2325-2338}}, month = {{MAR 7}}, abstract = {{We analyse the problem of comparing unitary transformations. The task is to decide, with minimal resources and maximal reliability, whether two given unitary transformations are identical or different. It is possible to make such. comparisons without obtaining any information about the individual transformations. Different comparison strategies are presented and compared with respect to their efficiency. With an interferometric setup, it is possible to compare two unitary transforms using only one test particle. Another strategy makes use of a two-particle singlet state. This strategy is more efficient than using a non-entangled two-particle test state, thus demonstrating the benefit of entanglement. Generalizations to higher.-dimensional transforms and to more than two transformations are made.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Andersson, E (Reprint Author), Univ Strathclyde, Dept Phys, Glasgow G4 0NG, Lanark, Scotland. Univ Strathclyde, Dept Phys, Glasgow G4 0NG, Lanark, Scotland. Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic.}}, doi = {{10.1088/0305-4470/36/9/310}}, issn = {{0305-4470}}, keywords-plus = {{ENTANGLEMENT; PRECISION; STATES}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary; Physics, Mathematical}}, researcherid-numbers = {{Andersson, Erika/D-1139-2013}}, orcid-numbers = {{Andersson, Erika/0000-0001-5856-6806}}, number-of-cited-references = {{21}}, times-cited = {{9}}, journal-iso = {{J. Phys. A-Math. Gen.}}, doc-delivery-number = {{661EU}}, unique-id = {{ISI:000181878900011}} }
@article{ISI:000180674100003, author = {Barnett, SM and Chefles, A and Jex, I}, title = {{Comparison of two unknown pure quantum states}}, journal = {{PHYSICS LETTERS A}}, year = {{2003}}, volume = {{307}}, number = {{4}}, pages = {{189-195}}, month = {{FEB 3}}, abstract = {{Can we establish whether or not two quantum systems have been prepared in the same state? We investigate the possibility of universal unambiguous state comparison. We show that it is impossible to conclusively identify two pure unknown states as being identical, and construct the optimal measurement for conclusively identifying them as being different. We then derive optimal strategies for state comparison when the state of each system is one of two known states. (C) 2002 Elsevier Science B.V. All rights reserved.}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{Chefles, A (Reprint Author), Univ Hertfordshire, Dept Phys Sci, Hatfield AL10 9AB, Herts, England. Univ Hertfordshire, Dept Phys Sci, Hatfield AL10 9AB, Herts, England. Univ Strathclyde, Dept Phys \& Appl Phys, Glasgow G4 0NG, Lanark, Scotland. Czech Tech Univ, FANS, Dept Phys, Prague 11519, Czech Republic.}}, doi = {{10.1016/S0375-9601(02)01602-X}}, issn = {{0375-9601}}, keywords = {{quantum mechanics; quantum information; quantum measurement}}, keywords-plus = {{DISCRIMINATION}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, number-of-cited-references = {{16}}, times-cited = {{56}}, journal-iso = {{Phys. Lett. A}}, doc-delivery-number = {{640EC}}, unique-id = {{ISI:000180674100003}} }
@article{ISI:000181566900019, author = {Jex, I and Alber, G and Barnett, SM and Delgado, A}, title = {{Antisymmetric multi-partite quantum states and their applications}}, journal = {{FORTSCHRITTE DER PHYSIK-PROGRESS OF PHYSICS}}, year = {{2003}}, volume = {{51}}, number = {{2-3}}, pages = {{172-178}}, note = {{9th Central European Workshop on Quantum Optics, SZEGED, HUNGARY, MAY 03-06, 2002}}, abstract = {{Entanglement is a powerful resource for processing quantum information. In this context pure, maximally entangled states have received considerable attention. In the case of bipartite qubit-systems the four orthonormal Bell-states are of this type. One of these Bell states, the singlet Bell-state, has the additional property of being antisymmetric with respect to particle exchange. In this contribution we discuss possible generalizations of this antisymmetric Bell-state to cases with more than two particles and with single-particle Hilbert spaces involving more than two dimensions. We review basic properties of these totally antisymmetric states. Among possible applications of this class of states we analyze a new quantum key sharing protocol and methods for comparing quantum states.}}, publisher = {{WILEY-BLACKWELL}}, address = {{COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA}}, type = {{Article; Proceedings Paper}}, language = {{English}}, affiliation = {{Jex, I (Reprint Author), Czech Tech Univ, Dept Phys, FNSPE, Brehova 7, Prague 11519, Czech Republic. Czech Tech Univ, Dept Phys, FNSPE, Prague 11519, Czech Republic. Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany. Univ Strathclyde, Dept Phys \& Appl Phys, Glasgow Q4 0NG, Lanark, Scotland. Univ New Mexico, Dept Phys \& Astron, Albuquerque, NM 87131 USA.}}, doi = {{10.1002/prop.200310021}}, issn = {{0015-8208}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{jex@br.fjfi.cvut.cz}}, researcherid-numbers = {{Delgado, Aldo/K-7564-2012}}, number-of-cited-references = {{7}}, times-cited = {{7}}, journal-iso = {{Fortschritte Phys.-Prog. Phys.}}, doc-delivery-number = {{655RR}}, unique-id = {{ISI:000181566900019}} }
@article{ISI:000176853700002, author = {Meneghini, S and Jex, I and Schleich, WP and Yakovlev, VP}, title = {{Reshaping of atomic waves with two-dimensional optical crystals}}, journal = {{JOURNAL OF OPTICS B-QUANTUM AND SEMICLASSICAL OPTICS}}, year = {{2002}}, volume = {{4}}, number = {{3}}, pages = {{165-171}}, month = {{JUN}}, abstract = {{We study the dynamics of atomic waves in a two-dimensional light crystal formed by two crossed standing laser fields. The longitudinal modulation of the crystal with the Doppler frequency significantly influences the transversal spatial modulation of the atomic wave. Near the doppleron resonance the atomic density shows a fractional space period. In this case a normally incident wave gives rise to an almost perfect conversion into the first momentum components and the light crystal acts as a highly efficient beamsplitter. The crossing angle, determining the Doppler frequency, is the easy-to-control parameter of the system.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Meneghini, S (Reprint Author), Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Czech Tech Univ, Dept Phys, FJFI, Prague 11519, Czech Republic. Moscow Engn Phys Inst, Moscow 115409, Russia.}}, doi = {{10.1088/1464-4266/4/3/301}}, issn = {{1464-4266}}, keywords = {{atom optics; Bragg diffraction; population conversion}}, keywords-plus = {{STANDING LIGHT-WAVE; BRAGG SCATTERING}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, number-of-cited-references = {{24}}, times-cited = {{0}}, journal-iso = {{J. Opt. B-Quantum Semicl. Opt.}}, doc-delivery-number = {{573WA}}, unique-id = {{ISI:000176853700002}} }
@article{ISI:000175743800026, author = {Torma, P and Jex, I and Schleich, WP}, title = {{Localization and diffusion in Ising-type quantum networks}}, journal = {{PHYSICAL REVIEW A}}, year = {{2002}}, volume = {{65}}, number = {{5, A}}, month = {{MAY}}, abstract = {{We investigate the effect of phase randomness in Ising-type quantum networks. These networks model a large class of physical systems. They describe micro- and nanostructures or arrays of optical elements such as beam splitters (interferometers) or parameteric amplifiers. Most of these stuctures are promising candidates for quantum information processing networks. We demonstrate that such systems exhibit two very distinct types of behavior. For certain network configurations (parameters), they show quantum localization similar to Anderson localization whereas classical stochastic behavior is observed in other cases. We relate these findings to the standard theory of quantum localization.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Torma, P (Reprint Author), Univ Jyvaskyla, Dept Phys, POB 35, FIN-40351 Jyvaskyla, Finland. Univ Jyvaskyla, Dept Phys, FIN-40351 Jyvaskyla, Finland. Helsinki Univ Technol, Lab Computat Engn, FIN-02015 Helsinki, Finland. Czech Tech Univ, FNSPE, Dept Phys, Prague 11519 1, Czech Republic. Univ Ulm, Abt Quantenphys, D-89081 Ulm, Germany.}}, doi = {{10.1103/PhysRevA.65.052110}}, article-number = {{052110}}, issn = {{1050-2947}}, keywords-plus = {{LANDAU-ZENER ANTICROSSINGS; TIME EVOLUTION; ATOMS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{30}}, times-cited = {{12}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{554PC}}, unique-id = {{ISI:000175743800026}} }
@article{ISI:000208901700003, author = {Alber, Gernot and Delgado, Aldo and Jex, Igor}, title = {{OPTIMAL TWO-PARTICLE ENTANGLEMENT BY UNIVERSAL QUANTUM PROCESSES}}, journal = {{QUANTUM INFORMATION \& COMPUTATION}}, year = {{2001}}, volume = {{1}}, number = {{3}}, pages = {{33-51}}, month = {{NOV}}, abstract = {{Within the class of all possible universal (covariant) two-particle quantum processes in arbitrary dimensional Hilbert spaces those universal quantum processes are determined whose output states optimize the recently proposed entanglement measure of Vidal and Werner. It is demonstrated that these optimal entanglement processes belong to a one-parameter family of universal entanglement processes whose output states do not contain any separable components. It is shown that these optimal universal entanglement processes generate antisymmetric output states and, with the single exception of qubit systems, they preserve information about the initial input state.}}, publisher = {{RINTON PRESS, INC}}, address = {{565 EDMUND TERRACE, PARAMUS, NJ 07652 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Alber, G (Reprint Author), Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Alber, Gernot; Delgado, Aldo, Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Jex, Igor, FJFI CVUT, Dept Phys, Prague 11519 1, Czech Republic.}}, issn = {{1533-7146}}, keywords = {{Entanglement; universal quantum processes; quantum cloning}}, research-areas = {{Computer Science; Physics}}, web-of-science-categories = {{Computer Science, Theory \& Methods; Physics, Particles \& Fields; Physics, Mathematical}}, funding-acknowledgement = {{DFG within the SPP `Quanteninformationsverarbeitung'; European Commission {[}IST-1999-13021]; European Science Foundation; DAAD; DLR; Ministry of Education of the Czech Republic}}, funding-text = {{This work is supported by the DFG within the SPP `Quanteninformationsverarbeitung', by the programmes `QUBITS' (IST-1999-13021) and `QUEST' of the European Commission, by the European Science Foundation within the `QUIT' programme, by the DAAD, by the DLR and by the Ministry of Education of the Czech Republic.}}, number-of-cited-references = {{20}}, times-cited = {{5}}, journal-iso = {{Quantum Inform. Comput.}}, doc-delivery-number = {{V31RW}}, unique-id = {{ISI:000208901700003}} }
@article{ISI:000172118600011, author = {Alber, G and Delgado, A and Gisin, N and Jex, I}, title = {{Efficient bipartite quantum state purification in arbitrary dimensional Hilbert spaces}}, journal = {{JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL}}, year = {{2001}}, volume = {{34}}, number = {{42}}, pages = {{8821-8833}}, month = {{OCT 26}}, abstract = {{A new purification scheme is proposed which applies to arbitrary dimensional bipartite quantum systems. It is based on the repeated application of a special class of nonlinear quantum maps and a single, local unitary operation. This special class of nonlinear quantum maps is generated in a natural way by a Hermitian generalized XOR-gate. The proposed purification scheme offers two major advantages, namely it does not require local depolarization operations at each step of the purification procedure and it purifies more efficiently than other known purification schemes.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Alber, G (Reprint Author), Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Univ Geneva, Grp Appl Phys, CH-1211 Geneva 4, Switzerland. Czech Tech Univ, Dept Phys, FJFI, Prague 11519 1, Czech Republic.}}, doi = {{10.1088/0305-4470/34/42/307}}, issn = {{0305-4470}}, keywords-plus = {{ERROR-CORRECTION; NOISY CHANNELS; COMMUNICATION; ENTANGLEMENT; SEPARABILITY; COMPUTATION; GATES}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary; Physics, Mathematical}}, researcherid-numbers = {{Delgado, Aldo/K-7564-2012}}, number-of-cited-references = {{21}}, times-cited = {{43}}, journal-iso = {{J. Phys. A-Math. Gen.}}, doc-delivery-number = {{491PZ}}, unique-id = {{ISI:000172118600011}} }
@article{ISI:000171981300001, author = {Jex, I}, title = {{Foreword}}, journal = {{FORTSCHRITTE DER PHYSIK-PROGRESS OF PHYSICS}}, year = {{2001}}, volume = {{49}}, number = {{10-11}}, pages = {{899}}, publisher = {{WILEY-V C H VERLAG GMBH}}, address = {{PO BOX 10 11 61, D-69451 BERLIN, GERMANY}}, type = {{Editorial Material}}, language = {{English}}, doi = {{10.1002/1521-3978(200110)49:10/11<899::AID-PROP899>3.0.CO;2-K}}, issn = {{0015-8208}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, number-of-cited-references = {{0}}, times-cited = {{0}}, journal-iso = {{Fortschritte Phys.-Prog. Phys.}}, doc-delivery-number = {{489FL}}, unique-id = {{ISI:000171981300001}} }
@article{ISI:000089908900012, author = {Bandilla, A and Drobny, G and Jex, I}, title = {{Parametric down-conversion and maximal pump depletion}}, journal = {{JOURNAL OF OPTICS B-QUANTUM AND SEMICLASSICAL OPTICS}}, year = {{2000}}, volume = {{2}}, number = {{3}}, pages = {{265-270}}, month = {{JUN}}, abstract = {{Using the truncated Wigner function approach and the Bloembergen solutions for nondegenerate down-conversion we calculate the conversion efficiency of spontaneous parametric down-conversion. In addition we determine higher moments of the pump and signal photon number. We find the upper bound for the efficiency of energy transfer and give a physically intuitive explanation for its existence. The depletion of the pump mode is immediately characterized by a strong destruction of its coherence.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Bandilla, A (Reprint Author), HU Berlin, Inst Phys, AG Nichtkl Strahlung, Invalidenstr 110, D-10115 Berlin, Germany. HU Berlin, Inst Phys, AG Nichtkl Strahlung, D-10115 Berlin, Germany. Slovak Acad Sci, Inst Phys, Bratislava 84228, Slovakia. Czech Tech Univ, FNSPE, Dept Phys, Prague 11519 1, Czech Republic. Univ Ulm, Abt Quanten Phys, D-89069 Ulm, Germany.}}, doi = {{10.1088/1464-4266/2/3/308}}, issn = {{1464-4266}}, keywords = {{nonlinear optics; parametric down-conversion; process efficiency}}, keywords-plus = {{QUANTUM; PHASE; STATES; FIELD}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, number-of-cited-references = {{24}}, times-cited = {{3}}, journal-iso = {{J. Opt. B-Quantum Semicl. Opt.}}, doc-delivery-number = {{364TK}}, unique-id = {{ISI:000089908900012}} }
@article{ISI:000087275000020, author = {Jex, I and Alber, G}, title = {{Rotational wavepacket dynamics of the C(60) molecule}}, journal = {{JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS}}, year = {{2000}}, volume = {{33}}, number = {{8}}, pages = {{1663-1674}}, month = {{APR 28}}, abstract = {{The wavepacket dynamics of (non-stationary) rotational quantum states of the C(60) molecule are investigated. It is demonstrated that the icosahedral symmetry of this molecule gives rise to a variety of peculiar coherence phenomena which are characteristic for this specific discrete symmetry group. On the one hand, the dynamics of these wavepackets reflects the underlying classical dynamics on the associated manifold of group space. On the other hand, these dynamics also exhibit characteristic quantum features such as the appearance of fractional revivals, of quantum tunnelling between different classically accessible regions of the associated manifold of group space and of cat-like quantum states which are generated in the course of the time evolution.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Jex, I (Reprint Author), Univ Ulm, Abt Quantenopt, Albert Einstein Allee 11, D-89069 Ulm, Germany. Univ Ulm, Abt Quantenopt, D-89069 Ulm, Germany. Czech Tech Univ, Dept Phys FJFI, Prague 11519 1, Stare Mesto, Czech Republic.}}, doi = {{10.1088/0953-4075/33/8/315}}, issn = {{0953-4075}}, keywords-plus = {{ICOSAHEDRAL MOLECULES; FINE-STRUCTURE}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{11}}, times-cited = {{1}}, journal-iso = {{J. Phys. B-At. Mol. Opt. Phys.}}, doc-delivery-number = {{318GF}}, unique-id = {{ISI:000087275000020}} }
@article{ISI:000084746000001, author = {Torma, P and Jex, I}, title = {{Hamiltonians for Ising-type quantum networks}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{2000}}, volume = {{47}}, number = {{1}}, pages = {{1-10}}, month = {{JAN 15}}, abstract = {{We derive Hamiltonians for quantum networks of Ising-type structure. These networks can be composed of simple optical elements such as beam splitters or parameteric amplifiers, similar structures appear also in a variety of systems with many intersecting energy levels. We give exact forms for the Hamiltonians and discuss their implications in certain limits.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Torma, P (Reprint Author), Univ Innsbruck, Inst Theoret Phys, Technikerstr 25, A-6020 Innsbruck, Austria. Univ Innsbruck, Inst Theoret Phys, A-6020 Innsbruck, Austria. Univ Ulm, Abt Quantenphys, D-89081 Ulm, Germany. Univ Innsbruck, Inst Phys Expt, A-6020 Innsbruck, Austria.}}, issn = {{0950-0340}}, keywords-plus = {{LANDAU-ZENER ANTICROSSINGS; TIME-EVOLUTION}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{15}}, times-cited = {{1}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{274CK}}, unique-id = {{ISI:000084746000001}} }
@article{ISI:000085681600024, author = {Meneghini, S and Jex, I and van Leeuwen, KAH and Kasimov, MR and Schleich, WP and Yakovlev, VP}, title = {{Atomic motion in longitudinally modulated light crystals}}, journal = {{LASER PHYSICS}}, year = {{2000}}, volume = {{10}}, number = {{1}}, pages = {{116-122}}, month = {{JAN-FEB}}, abstract = {{We study the dynamics of atomic waves in longitudinally modulated light crystals using an effective complex potential with time (space) dependent detuning. In the weak coupling regime we predict a sharp asymmetry of the scattering probability near the Bragg angle. In the strong coupling case we introduce the concept of a light crystal with ``complex kick.{''} We have found that the initially blue detuned crystal is much more transparent for atomic waves. Moreover, the probability distribution of the outgoing wave shows carpetlike interference structure.}}, publisher = {{MAIK NAUKA/INTERPERIODICA/SPRINGER}}, address = {{233 SPRING ST, NEW YORK, NY 10013-1578 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Meneghini, S (Reprint Author), Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Univ Ulm, Abt Quantenphys, D-89069 Ulm, Germany. Czech Tech Univ, Dept Phys, FJFI, Prague, Czech Republic. Eindhoven Univ Technol, Dept Phys, NL-5600 MB Eindhoven, Netherlands. Moscow Engn Phys Inst, Moscow 115409, Russia.}}, issn = {{1054-660X}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, author-email = {{schleich@physik.uni-ulm.de}}, number-of-cited-references = {{11}}, times-cited = {{4}}, journal-iso = {{Laser Phys.}}, doc-delivery-number = {{290NE}}, unique-id = {{ISI:000085681600024}} }
@inproceedings{ISI:000165892200071, author = {Bandilla, A and Drobny, G and Jex, I}, editor = {{Kumar, P and DAriano, GM and Hirota, O}}, title = {{Energy transfer in parametric down-conversion}}, booktitle = {{QUANTUM COMMUNICATION, COMPUTING, AND MEASUREMENT 2}}, year = {{2000}}, pages = {{521-525}}, note = {{4th International Conference on Quantum Communication, Measurement, and Computing, NORTHWESTERN UNIV, EVANSTON, IL, AUG 22-27, 1998}}, organization = {{Tamagawa Univ; NW Univ; Natl Secur Agcy; USN Off Res}}, publisher = {{KLUWER ACADEMIC/PLENUM PUBL}}, address = {{233 SPRING ST, NEW YORK, NY 10013 USA}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{Bandilla, A (Reprint Author), Humboldt Univ, AG Nichtklass Strahlung, Inst Phys, Invalidenstr 110, D-10115 Berlin, Germany. Humboldt Univ, AG Nichtklass Strahlung, Inst Phys, D-10115 Berlin, Germany.}}, isbn = {{0-306-46307-5}}, keywords-plus = {{QUANTUM}}, research-areas = {{Computer Science; Engineering; Optics; Physics}}, web-of-science-categories = {{Computer Science, Information Systems; Engineering, Electrical \& Electronic; Optics; Physics, Mathematical}}, number-of-cited-references = {{15}}, times-cited = {{0}}, doc-delivery-number = {{BR21Y}}, unique-id = {{ISI:000165892200071}} }
@article{ISI:000079233200064, author = {Horne, M and Jex, I and Zeilinger, A}, title = {{Schrodinger wave functions in strong periodic potentials with applications to atom optics}}, journal = {{PHYSICAL REVIEW A}}, year = {{1999}}, volume = {{59}}, number = {{3}}, pages = {{2190-2202}}, month = {{MAR}}, abstract = {{When an atom diffracts in intense standing light, the periodic potential can be too strong for known solutions of the Schrodinger equation. We present general solutions of Schrodinger's equation in strong sinusoidal media, thus generalizing dynamical diffraction theory. The solutions exhibit rich generalizations of the pendellosung phenomena. {[}S1050-2947(99)01203-2].}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Horne, M (Reprint Author), Stonehill Coll, N Easton, MA 02357 USA. Stonehill Coll, N Easton, MA 02357 USA. Czech Tech Univ, Fak Jaderna \& Fyz Inzenyrska, Prague 11519 1, Stare Mesto, Czech Republic. Univ Innsbruck, Inst Expt Phys, A-6020 Innsbruck, Austria.}}, doi = {{10.1103/PhysRevA.59.2190}}, issn = {{1050-2947}}, keywords-plus = {{LIGHT}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{14}}, times-cited = {{13}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{177WC}}, unique-id = {{ISI:000079233200064}} }
@article{ISI:000081422100003, author = {Torma, P and Jex, I}, title = {{Properties of Ising-type linear networks}}, journal = {{JOURNAL OF OPTICS B-QUANTUM AND SEMICLASSICAL OPTICS}}, year = {{1999}}, volume = {{1}}, number = {{1}}, pages = {{8-13}}, month = {{FEB}}, abstract = {{We study some of the mathematical properties of quantum networks with Ising-type nearest-neighbour structure. Based on the formal properties the physical behaviour of the network, such as destructive and constructive interference, is discussed.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Torma, P (Reprint Author), Univ Innsbruck, Inst Expt Phys, Technikerstr 25, A-6020 Innsbruck, Austria. Univ Innsbruck, Inst Expt Phys, A-6020 Innsbruck, Austria. Czech Tech Univ, Dept Phys, FNSPE, Prague 11519 1, Czech Republic. Univ Innsbruck, Inst Expt Phys, A-6020 Innsbruck, Austria.}}, doi = {{10.1088/1464-4266/1/1/002}}, issn = {{1464-4266}}, keywords = {{Ising model; linear quantum networks}}, keywords-plus = {{LANDAU-ZENER ANTICROSSINGS; TIME EVOLUTION; QUANTUM; PHASE}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{21}}, times-cited = {{10}}, journal-iso = {{J. Opt. B-Quantum Semicl. Opt.}}, doc-delivery-number = {{216CC}}, unique-id = {{ISI:000081422100003}} }
@article{ISI:000078407200002, author = {Konopka, M and Jex, I}, title = {{Exact solutions for nonlinear Hamiltonians}}, journal = {{CZECHOSLOVAK JOURNAL OF PHYSICS}}, year = {{1998}}, volume = {{48}}, number = {{12}}, pages = {{1537-1553}}, month = {{DEC}}, abstract = {{We find the eigenvalues and eigenvectors of two nonlinear Hamiltonians describing the interaction between a two-level system and a quantized linear harmonic oscillator. In the first case we obtain exact isolated solutions for the Hamiltonian used as a model of an ion in a harmonic trap and interacting with a laser field, not restricted to the Lamb-Dicke limit. After projecting these eigenstates onto one of the levels of the two-level system the oscillator state is described by a finite superposition of Fock states. In the second case me consider a Hamiltonian, with a squeeze operator in the interaction part. We give perturbation results in the weak-coupling limit and results obtained by numerical diagonalization for the strong coupling limit. Non-classical results are pointed out also in this case.}}, publisher = {{CZECHOSLOVAK JNL OF PHYSICS}}, address = {{FYZIKALNI USTAV AV NA SLOVANCE 2, PRAGUE 180 40, CZECH REPUBLIC}}, type = {{Article}}, language = {{English}}, affiliation = {{Konopka, M (Reprint Author), Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, Brehova 7, CR-11519 Prague, Czech Republic. Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic. Slovak Acad Sci, Inst Phys, Bratislava 84228, Slovakia. Comenius Univ, Fac Math \& Phys, Dept Opt, Bratislava 84215, Slovakia.}}, doi = {{10.1023/A:1022866722760}}, issn = {{0011-4626}}, keywords-plus = {{2-LEVEL SYSTEM; QUANTUM}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, author-email = {{konopka@fmph.uniba.sk jex@br.fjfi.cvut.cz}}, number-of-cited-references = {{22}}, times-cited = {{0}}, journal-iso = {{Czech. J. Phys.}}, doc-delivery-number = {{163LN}}, unique-id = {{ISI:000078407200002}} }
@article{ISI:000076960300017, author = {Bandilla, A and Drobny, G and Jex, I}, title = {{The classical parametric approximation for three-wave interactions}}, journal = {{OPTICS COMMUNICATIONS}}, year = {{1998}}, volume = {{156}}, number = {{1-3}}, pages = {{112-122}}, month = {{NOV 1}}, abstract = {{We study sufficient conditions for the applicability of the classical parametric approximation in three-wave interactions when the pump intensity is very large compared to signal and idler intensity. To derive such conditions we express the exact classical solutions given by Jacobian elliptic functions in terms of hyperbolic functions. Thereby the first minimum of the pump intensity is correctly described but the periodicity is lost. We derive new approximations for the initial conditions using pump coordinate scaling and find the interval that defines complete pump depletion. We show that the classical parametric approximation with a fixed and sharp pump amplitude and phase can be used for an increasing fraction of this interval if the pump intensity is made to grow. By choosing higher and higher pump intensities the nonlinearity is shifted to the end of that interval. As an instructive example for the application of these findings the generation of two-mode squeezing is briefly considered. (C) 1998 Elsevier Science B.V. All rights reserved.}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{Bandilla, A (Reprint Author), Humboldt Univ, Lehrstuhl Nichtklass Strahlung, Rudower Chaussee 5,Haus 10-16, D-12484 Berlin, Germany. Humboldt Univ, Lehrstuhl Nichtklass Strahlung, D-12484 Berlin, Germany. Slovak Acad Sci, Inst Phys, Bratislava 84228, Slovakia. Czech Tech Univ, Fac Nucl Sci \& Phys Engn, Dept Phys, CR-11519 Prague, Czech Republic.}}, doi = {{10.1016/S0030-4018(98)00404-0}}, issn = {{0030-4018}}, keywords-plus = {{AMPLIFIER; PUMP}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{16}}, times-cited = {{8}}, journal-iso = {{Opt. Commun.}}, doc-delivery-number = {{138FH}}, unique-id = {{ISI:000076960300017}} }
@inproceedings{ISI:000076377700116, author = {Bandilla, A and Drobny, G and Jex, I}, editor = {{Kasperkovitz, P and Grau, D}}, title = {{Quantum description of nonlinearly coupled oscillators via classical trajectories}}, booktitle = {{5TH WIGNER SYMPOSIUM, PROCEEDINGS}}, year = {{1998}}, pages = {{389-391}}, note = {{5th Wigner Symposium, VIENNA, AUSTRIA, AUG 25-29, 1997}}, abstract = {{We discuss the usefulness of the Wigner function description via classical trajectories in the example of the three-wave interaction with a strong coherent pump.}}, publisher = {{WORLD SCIENTIFIC PUBL CO PTE LTD}}, address = {{PO BOX 128 FARRER RD, SINGAPORE 9128, SINGAPORE}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{Bandilla, A (Reprint Author), Humboldt Univ, Lehrstuhl Nichtklass Strahlung, D-2484 Berlin, Germany. Humboldt Univ, Lehrstuhl Nichtklass Strahlung, D-2484 Berlin, Germany.}}, isbn = {{981-02-3464-3}}, research-areas = {{Mathematics; Physics}}, web-of-science-categories = {{Mathematics, Applied; Physics, Multidisciplinary; Physics, Mathematical}}, number-of-cited-references = {{0}}, times-cited = {{0}}, doc-delivery-number = {{BL70A}}, unique-id = {{ISI:000076377700116}} }
@article{ISI:000071541000005, author = {Tittonen, I and Stenholm, S and Jex, I}, title = {{Stepwise phase modulation of atoms coupled to a quasi-continuum of states in a cavity}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1998}}, volume = {{45}}, number = {{1}}, pages = {{23-33}}, month = {{JAN}}, abstract = {{We study the interaction of a small number of resonant two-level atoms in a cavity coupled to a quasi-continuum of cavity modes. During the interaction we induce externally a phase step to one of the atoms. As a result an enhancement in the photon emission to the field is observed. The phase step is obtained by a pulse which causes the atom to be off-resonance for a short lime interval. The effect is strongest in cases where the number of atoms is small. The enhancement is not restricted to a small parameter range but should be observable in many systems even though the pi phase shift gives the best enhancement.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNPOWDER SQUARE, LONDON EC4A 3DE, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{Tittonen, I (Reprint Author), Univ Konstanz, Fak Phys, M 696, D-78434 Constance, Germany. Univ Helsinki, Theoret Phys Res Inst, FIN-00014 Helsinki, Finland. Humboldt Univ, Max Planck Gesell, Arbeitsgrp Nichtklass Strahlung, D-12484 Berlin, Germany.}}, issn = {{0950-0340}}, keywords-plus = {{GAMMA-ECHO; PHOTOEXCITATION; RECURRENCES}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Tittonen, Ilkka/C-6649-2013}}, orcid-numbers = {{Tittonen, Ilkka/0000-0002-2985-9789}}, number-of-cited-references = {{16}}, times-cited = {{2}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{YR883}}, unique-id = {{ISI:000071541000005}} }
@article{ISI:A1997YH58600028, author = {Paul, H and Torma, P and Kiss, T and Jex, I}, title = {{Two-mode state reconstruction using photon chopping}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1997}}, volume = {{44}}, number = {{11-12}}, pages = {{2395-2404}}, month = {{NOV-DEC}}, abstract = {{The reconstruction of the complete quantum state of a pure-state two-mode field is shown to be possible by the photon-chopping method, that is, by spreading the signal with balanced multiports over an array of detectors and by measuring coincidences. In particular, correlations between the two modes can be detected with high efficiency.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{Paul, H (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ABREITSGRP NICHTKLASS STRAHLUNG,RUDOWER CHAUSSEE 5,D-12484 BERLIN,GERMANY. UNIV ULM,ABT QUANTENPHYS,D-89069 ULM,GERMANY. HUNGARIAN ACAD SCI,CRYSTAL PHYS RES LAB,H-1502 BUDAPEST,HUNGARY. SLOVAK ACAD SCI,INST PHYS,BRATISLAVA 84228,SLOVAKIA. CZECH TECH UNIV,FAC NUCL SCI \& PHYS ENGN,DEPT PHYS,PRAGUE 11519 1,CZECH REPUBLIC.}}, issn = {{0950-0340}}, keywords-plus = {{OPTICAL HOMODYNE TOMOGRAPHY; QUANTUM-STATE; DENSITY-MATRIX; LIGHT; STATISTICS; NUMBER; PHASE; VACUUM}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{31}}, times-cited = {{5}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{YH586}}, unique-id = {{ISI:A1997YH58600028}} }
@article{ISI:A1997YF52900087, author = {Paul, H and Torma, P and Kiss, T and Jex, I}, title = {{Multiple coincidences and the quantum state reconstruction problem}}, journal = {{PHYSICAL REVIEW A}}, year = {{1997}}, volume = {{56}}, number = {{5}}, pages = {{4076-4085}}, month = {{NOV}}, abstract = {{We analyze the recently proposed method {[}H. Paul et al., Phys. Rev. Lett. 76, 2464 (1996)] for reconstructing the quantum state of a light field from multiple coincidences measured at the outputs of a passive multiport. We show that applying a large multiport the reconstruction of a pure state becomes possible using avalanche photodiode-type detectors. The presented simulations show that the photon chopping scheme is appropriate for the indirect measurement of the photon statistics of a weak nonclassical signal. {[}S1050-2947(97)07507-0].}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Paul, H (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,RUDOWER CHAUSSEE 5,D-12484 BERLIN,GERMANY. UNIV HELSINKI,THEORET PHYS RES INST,FIN-00014 HELSINKI,FINLAND. UNIV ULM,ABT QUANTENPHYS,D-89069 ULM,GERMANY. HUNGARIAN ACAD SCI,CRYSTAL PHYS RES LAB,H-1502 BUDAPEST,HUNGARY. SLOVAK ACAD SCI,INST PHYS,BRATISLAVA 84228,SLOVAKIA. CZECH TECH UNIV,FAC NUCL SCI \& PHYS ENGN,DEPT PHYS,CR-11519 PRAGUE,CZECH REPUBLIC.}}, doi = {{10.1103/PhysRevA.56.4076}}, issn = {{1050-2947}}, keywords-plus = {{OPTICAL HOMODYNE TOMOGRAPHY; DENSITY-MATRIX; PHASE-SPACE; SQUEEZED VACUUM; PHOTON-NUMBER; WAVE-FUNCTION; DISTRIBUTIONS; STATISTICS; ENDOSCOPY; MECHANICS}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{39}}, times-cited = {{7}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{YF529}}, unique-id = {{ISI:A1997YF52900087}} }
@article{ISI:A1997WZ59000002, author = {Torma, P and Jex, I}, title = {{Two-mode entanglement in passive networks}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1997}}, volume = {{44}}, number = {{5}}, pages = {{875-882}}, month = {{MAY}}, abstract = {{We discuss the degree of entanglement for symmetric passive optical networks. As a measure of the entanglement we use the information entropy and compare our results for a general number N of inputs with the known results for a two-mode beam splitter. Special cases of interest are pointed out.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{Torma, P (Reprint Author), UNIV HELSINKI,RES INST THEORET PHYS,POB 9,SILTAVUORENPENGER 20C,FIN-00014 HELSINKI,FINLAND.}}, doi = {{10.1080/095003497153527}}, issn = {{0950-0340}}, keywords-plus = {{BEAM SPLITTER; PHOTON STATISTICS; QUANTUM-OPTICS; INPUT; SYSTEMS; STATES}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{25}}, times-cited = {{3}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{WZ590}}, unique-id = {{ISI:A1997WZ59000002}} }
@article{ISI:A1997WB98000013, author = {Drobny, G and Bandilla, A and Jex, I}, title = {{Quantum description of nonlinearly interacting oscillators via classical trajectories}}, journal = {{PHYSICAL REVIEW A}}, year = {{1997}}, volume = {{55}}, number = {{1}}, pages = {{78-93}}, month = {{JAN}}, abstract = {{We investigate systems of few harmonic oscillators with mutual nonlinear coupling. Using classical trajectories-the solutions of Hamiltonian equations of motion for a given nonlinear system-we construct the approximate quasiprobability distribution function in phase space that enables a quantum description. The nonclassical effects (quantum noise reduction) and their scaling laws can be so studied for high excitation numbers. In particular, the harmonic oscillators represent modes of the electromagnetic field and the Hamiltonians under consideration describe representative nonlinear optical processes (multiwave mixings). The range of the validity of the approximation for Wigner and Husimi functions evolved within the classical Liouville equation is discussed for a diverse class of initial conditions, including those without classical counterparts, e.g., Fock states.}}, publisher = {{AMER PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Drobny, G (Reprint Author), HUMBOLDT UNIV BERLIN, MAX PLANCK GESELL, AG NICHTKLASS STRAHLUNG, RUDOWER CHAUSSEE 5, BERLIN, GERMANY. CZECH TECH UNIV, FJFI, DEPT PHYS, PRAGUE 11519 1, CZECH REPUBLIC. SLOVAK ACAD SCI, INST PHYS, BRATISLAVA 84228, SLOVAKIA.}}, doi = {{10.1103/PhysRevA.55.78}}, issn = {{1050-2947}}, keywords-plus = {{PHOTON DOWN-CONVERSION; PARAMETRIC OSCILLATOR; PHASE-SPACE; 2ND-HARMONIC GENERATION; ANHARMONIC-OSCILLATOR; LANGEVIN EQUATION; FLUCTUATIONS; AMPLIFIER; STATES; PUMP}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{61}}, times-cited = {{23}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{WB980}}, unique-id = {{ISI:A1997WB98000013}} }
@article{ISI:A1996VQ69600015, author = {Torma, P and Jex, I}, title = {{Plate beam splitters and symmetric multiports}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1996}}, volume = {{43}}, number = {{11}}, pages = {{2403-2408}}, month = {{NOV}}, abstract = {{We show that for experimental arrangements with few nonvacuum inputs the fully symmetric multiport can be replaced by a simpler partially symmetric multiport. This device is equivalent to a beam splitter arrangement where the number of necessary beam splitters increases linearly with increasing number of inputs, that is it is considerably simpler to realize owning to the smaller number of components needed.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{Torma, P (Reprint Author), UNIV HELSINKI,THEORET PHYS RES INST,POB 9 SILTAVUORENPENGER 20C,FIN-00014 HELSINKI,FINLAND.}}, doi = {{10.1080/095003496154635}}, issn = {{0950-0340}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{15}}, times-cited = {{10}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{VQ696}}, unique-id = {{ISI:A1996VQ69600015}} }
@article{ISI:A1996UY52400023, author = {Bandilla, A and Drobny, G and Jex, I}, title = {{Phase-space motion in parametric three-wave interaction}}, journal = {{OPTICS COMMUNICATIONS}}, year = {{1996}}, volume = {{128}}, number = {{4-6}}, pages = {{353-362}}, month = {{JUL 15}}, abstract = {{We study the interaction of three modes in phi((2)) media in the classical as well as in the quantum picture. We show that it is possible to distinguish two basic forms of phase-space motion depending on the value of the integral of motion Gamma in the classical formulation or the (initial) mean value of the interaction Hamiltonian in the quantum formulation. The quantum and classical pictures are compared using a simulation of the Husimi Q function via classical trajectories for an ensemble of phase-space points. The very good correspondence between the two pictures is shown to last for a significant interaction time and can be investigated for arbitrary initial intensities.}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{Bandilla, A (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTLASS STRAHLUNG,RUDOWER CHAUSSEE 5,D-12484 BERLIN,GERMANY. SLOVAK ACAD SCI,INST PHYS,BRATISLAVA 84228,SLOVAKIA.}}, doi = {{10.1016/0030-4018(96)00136-8}}, issn = {{0030-4018}}, keywords-plus = {{QUANTUM; AMPLIFICATION; CONVERSION; AMPLIFIER; STATE; MODE}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{33}}, times-cited = {{13}}, journal-iso = {{Opt. Commun.}}, doc-delivery-number = {{UY524}}, unique-id = {{ISI:A1996UY52400023}} }
@article{ISI:A1996UC77700015, author = {Paul, H and Torma, P and Kiss, T and Jex, I}, title = {{Photon chopping: New way to measure the quantum state of light}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{1996}}, volume = {{76}}, number = {{14}}, pages = {{2464-2467}}, month = {{APR 1}}, abstract = {{We propose the use of a balanced 2N-port as a technique to measure the pure quantum state of a single-mode light field. In our scheme the coincidence signals of simple, realistic photodetectors are recorded at the output of the 2N-port. We show that applying different arrangements both the modulus and the phase of the coefficients in a finite superposition state can be measured. In particular, the photon statistics can be so measured with currently available devices.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Paul, H (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,RUDOWER CHAUSSEE 5,D-12484 BERLIN,GERMANY. UNIV HELSINKI,THEORET PHYS RES INST,SF-00014 HELSINKI,FINLAND. HUNGARIAN ACAD SCI,CRYSTAL PHYS RES LAB,H-1502 BUDAPEST,HUNGARY. SLOVAK ACAD SCI,INST PHYS,BRATISLAVA 84228,SLOVAKIA. CZECH TECH UNIV,FAC NUCL SCI \& PHYS ENGN,DEPT PHYS,CR-11519 PRAGUE,CZECH REPUBLIC.}}, doi = {{10.1103/PhysRevLett.76.2464}}, issn = {{0031-9007}}, keywords-plus = {{OPTICAL HOMODYNE TOMOGRAPHY; PHASE; DISTRIBUTIONS}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, researcherid-numbers = {{Kiss, Tamas/B-9228-2009 Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{22}}, times-cited = {{94}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{UC777}}, unique-id = {{ISI:A1996UC77700015}} }
@article{ISI:A1996UE67100014, author = {Tittonen, I and Stenholm, S and Jex, I}, title = {{Effect of a phase step on two-level atoms in a cavity}}, journal = {{OPTICS COMMUNICATIONS}}, year = {{1996}}, volume = {{124}}, number = {{3-4}}, pages = {{271-276}}, month = {{MAR 1}}, abstract = {{We analyze the dynamics of an excited two-level atom in the presence of other deexcited atoms in a cavity. We show, that due to an instantaneous phase shift experienced by one of the atoms, the probability for emitting a photon into the cavity can be increased. In the special case of only two atoms in the cavity we show that the system with certainty can release a photon that is otherwise partially trapped.}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{ACAD FINLAND,TURKU,FINLAND. UNIV HELSINKI,THEORET PHYS RES INST,SF-00014 HELSINKI,FINLAND. HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,D-12484 BERLIN,GERMANY.}}, doi = {{10.1016/0030-4018(95)00700-8}}, issn = {{0030-4018}}, keywords-plus = {{SPONTANEOUS EMISSION; GAMMA-ECHO; ENTANGLEMENT}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Tittonen, Ilkka/C-6649-2013}}, orcid-numbers = {{Tittonen, Ilkka/0000-0002-2985-9789}}, number-of-cited-references = {{15}}, times-cited = {{8}}, journal-iso = {{Opt. Commun.}}, doc-delivery-number = {{UE671}}, unique-id = {{ISI:A1996UE67100014}} }
@article{ISI:A1996TZ55100004, author = {Torma, P and Jex, I and Stenholm, S}, title = {{Beam splitter realizations of totally symmetric mode couplers}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1996}}, volume = {{43}}, number = {{2}}, pages = {{245-251}}, month = {{FEB}}, abstract = {{We discuss the symmetric multiport and show in a constructive way how it can be decomposed into a set of beam splitters. Based on the decomposition we estimate the number of beam splitters needed. It is shown that for more than three input ports the number of beam splitters needed is less than the number indicated by the standard decomposition scheme.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{Torma, P (Reprint Author), UNIV HELSINKI,THEORET PHYS RES INST,SILTAVUORENPENGER 20C,SF-00014 HELSINKI,FINLAND. ACAD FINLAND,HELSINKI,FINLAND.}}, doi = {{10.1080/095003496156129}}, issn = {{0950-0340}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{14}}, times-cited = {{17}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{TZ551}}, unique-id = {{ISI:A1996TZ55100004}} }
@inproceedings{ISI:A1996BG08Q00081, author = {Torma, P and Stenholm, S and Jex, I}, editor = {{Eberly, JH and Mandel, L and Wolf, E}}, title = {{Quantum theory of optical networks}}, booktitle = {{COHERENCE AND QUANTUM OPTICS VII}}, year = {{1996}}, pages = {{415-416}}, note = {{7th Rochester Conference on Coherence and Quantum Optics, UNIV ROCHESTER, ROCHESTER, NY, JUN 07-10, 1995}}, organization = {{Amer Phys Soc; Opt Soc Amer; Int Union Pure \& Appl Phys; Univ Rochester}}, publisher = {{PLENUM PRESS DIV PLENUM PUBLISHING CORP}}, address = {{233 SPRING ST, NEW YORK, NY 10013}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{UNIV HELSINKI,THEORET PHYS RES INST,FIN-00014 HELSINKI,FINLAND.}}, isbn = {{0-306-45314-2}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{0}}, times-cited = {{0}}, doc-delivery-number = {{BG08Q}}, unique-id = {{ISI:A1996BG08Q00081}} }
@inproceedings{ISI:A1996BG08Q00088, author = {Bandilla, A and Drobny, G and Jex, I}, editor = {{Eberly, JH and Mandel, L and Wolf, E}}, title = {{Three-wave mixing with entangled and disentangled states}}, booktitle = {{COHERENCE AND QUANTUM OPTICS VII}}, year = {{1996}}, pages = {{429-430}}, note = {{7th Rochester Conference on Coherence and Quantum Optics, UNIV ROCHESTER, ROCHESTER, NY, JUN 07-10, 1995}}, organization = {{Amer Phys Soc; Opt Soc Amer; Int Union Pure \& Appl Phys; Univ Rochester}}, publisher = {{PLENUM PRESS DIV PLENUM PUBLISHING CORP}}, address = {{233 SPRING ST, NEW YORK, NY 10013}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{HUMBOLDT UNIV BERLIN,D-12484 BERLIN,GERMANY.}}, isbn = {{0-306-45314-2}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, number-of-cited-references = {{0}}, times-cited = {{0}}, doc-delivery-number = {{BG08Q}}, unique-id = {{ISI:A1996BG08Q00088}} }
@inproceedings{ISI:A1996BG08Q00208, author = {Leonhardt, U and Jex, I}, editor = {{Eberly, JH and Mandel, L and Wolf, E}}, title = {{Quantum-state tomography and quantum communication}}, booktitle = {{COHERENCE AND QUANTUM OPTICS VII}}, year = {{1996}}, pages = {{675-676}}, note = {{7th Rochester Conference on Coherence and Quantum Optics, UNIV ROCHESTER, ROCHESTER, NY, JUN 07-10, 1995}}, organization = {{Amer Phys Soc; Opt Soc Amer; Int Union Pure \& Appl Phys; Univ Rochester}}, publisher = {{PLENUM PRESS DIV PLENUM PUBLISHING CORP}}, address = {{233 SPRING ST, NEW YORK, NY 10013}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,D-12484 BERLIN,GERMANY.}}, isbn = {{0-306-45314-2}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, number-of-cited-references = {{0}}, times-cited = {{0}}, doc-delivery-number = {{BG08Q}}, unique-id = {{ISI:A1996BG08Q00208}} }
@article{ISI:A1996TR75000062, author = {Bandilla, A and Drobny, G and Jex, I}, title = {{Nondegenerate parametric interactions and nonclassical effects}}, journal = {{PHYSICAL REVIEW A}}, year = {{1996}}, volume = {{53}}, number = {{1}}, pages = {{507-516}}, month = {{JAN}}, abstract = {{We consider the classical and quantum-mechanical processes of three-wave interactions in different phase regimes and present numerical calculations for the quantum case, where all three modes are sizably excited from the beginning. These excitations are coherent so that various important phase regimes can be adjusted. In addition, one mode can also be prepared in a squeezed or Kerr state. The classical solutions are well known and are briefly summarized, but certain phase regimes are classically unexplored and we show here that they give interesting and surprising results. In the out-of-phase regime (where the photon numbers do not change in the first order of time) we get, with an initial Kerr state, strongly sub-Poissonian photon statistics in the signal after a short interaction time. This effect is limited by the classically described phase shifts that are present even in the parametric approximation. This nonclassical phenomenon (due to the Kerr state) helps us to understand similar nonclassical effects generated by entangled states of the pump and signal during sum-frequency generation.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{Bandilla, A (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,RUDOWER SHAUSSEE 5,D-12484 BERLIN,GERMANY. SLOVAK ACAD SCI,INST PHYS,BRATISLAVA 84228,SLOVAKIA.}}, doi = {{10.1103/PhysRevA.53.507}}, issn = {{1050-2947}}, keywords-plus = {{QUANTUM; INTERFEROMETER; AMPLIFICATION}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{20}}, times-cited = {{28}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{TR750}}, unique-id = {{ISI:A1996TR75000062}} }
@article{ISI:A1995TK65200063, author = {TORMA, P and STENHOLM, S and JEX, I}, title = {{MEASUREMENT AND PREPARATION USING 2 PROBE MODES}}, journal = {{PHYSICAL REVIEW A}}, year = {{1995}}, volume = {{52}}, number = {{6}}, pages = {{4812-4822}}, month = {{DEC}}, abstract = {{We consider the simultaneous measurement of two conjugate variables by coupling the system of interest to two independent probe modes. Our model consists of linearly coupled boson modes that can be realized by quantum optical fields in the rotating-wave approximation. We approach the setup both as a device to extract observable information and to prepare an emerging quantum state. The initial states of the probe modes and the coupling are utilized to optimize the operation in the various regimes. In contrast to the Arthurs and Kelly ideal scheme {[}Bell. Syst. Tech. J. 44, 725 (1965)], our more realistic coupling does not allow perfect operation but the ideal situations can be approximated closely. We discuss the conditions for maximum information transfer to the probe modes, information extraction with minimum disturbance of the system mode, and optimal state preparation for subsequent measurements. The minimum disturbance operation can be made to approximate a nondemolition measurement, especially when the information is carried in one quadrature component only. In the preparation mode, we find that the recording accuracy of the probe signals plays an essential role. We restrict the discussion to the first and second moments only, but the method can easily be generalized to any situation, Choosing all modes to be in squeezed coherent states originally, we can carry out analytical considerations; other cases can be treated numerically. The results are presented and discussed in detail as the paradigm of a class of realizable measurements.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{TORMA, P (Reprint Author), UNIV HELSINKI,THEORET PHYS RES INST,POB 9,SF-00014 HELSINKI,FINLAND. SLOVAK ACAD SCI,INST PHYS,BRATISLAVA 8428,SLOVAKIA. ACAD FINLAND,SF-00014 HELSINKI,FINLAND.}}, doi = {{10.1103/PhysRevA.52.4812}}, issn = {{1050-2947}}, keywords-plus = {{QUANTUM; PROBABILITY; HOMODYNE; NOISE; PHASE}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{25}}, times-cited = {{16}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{TK652}}, unique-id = {{ISI:A1995TK65200063}} }
@article{ISI:A1995TK65200067, author = {TORMA, P and STENHOLM, S and JEX, I}, title = {{HAMILTONIAN THEORY OF SYMMETRICAL OPTICAL NETWORK TRANSFORMS}}, journal = {{PHYSICAL REVIEW A}}, year = {{1995}}, volume = {{52}}, number = {{6}}, pages = {{4853-4860}}, month = {{DEC}}, abstract = {{We discuss the theory of extracting an interaction Hamiltonian from a preassigned unitary transformation of quantum states. Such a procedure is of significance in quantum computations and other optical information processing tasks. We particularize the problem to the construction of totally symmetric 2N peas as introduced by Zeilinger and his collaborators {[}A. Zeilinger, M. Zukowski, M. A. Home, H. J. Bernstein, and D. M. Greenberger, in Fundamental Aspects of Quantum Theory, edited by J. Anandan and J. J. Safko (World Scientific, Singapore, 1994)]. These are realized by the discrete Fourier transform,which simplifies the construction of the Hamiltonian by known methods of Linear algebra. The Hamiltonians found are discussed and alternative realizations of the Zeilinger class transformations are presented. We briefly discuss the applicability of the method to more general devices.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{TORMA, P (Reprint Author), THEORET PHYS RES INST,POB 9,SILTAVUORENPENGER 20C,SF-00014 HELSINKI,FINLAND. ACAD FINLAND,SF-00014 HELSINKI,FINLAND.}}, doi = {{10.1103/PhysRevA.52.4853}}, issn = {{1050-2947}}, keywords-plus = {{QUANTUM}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{20}}, times-cited = {{37}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{TK652}}, unique-id = {{ISI:A1995TK65200067}} }
@article{ISI:A1995TF68400013, author = {BANDILLA, A and DROBNY, G and JEX, I}, title = {{SUB-POISSONIAN PHOTON STATISTICS IN A 3-WAVE INTERACTION STARTING IN THE OUT-OF-PHASE REGIME}}, journal = {{PHYSICAL REVIEW LETTERS}}, year = {{1995}}, volume = {{75}}, number = {{22}}, pages = {{4019-4022}}, month = {{NOV 27}}, abstract = {{We present for the first time numerical and analytical calculations for the nonlinear interaction of three quantized waves all sizably excited from the beginning and having different phase relations. With a Kerr-state ansatz for the signal we get strongly sub-Poissonian photon statistics and conclude on similar effects by initially entangled states.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{BANDILLA, A (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,AKTIENGESELL NICHTKLASS STRAHLUNG,RUDOWER CHAUSSEE 5,D-12484 BERLIN,GERMANY. SLOVAK ACAD SCI,INST PHYS,BRATISLAVA 84228,SLOVAKIA.}}, doi = {{10.1103/PhysRevLett.75.4019}}, issn = {{0031-9007}}, keywords-plus = {{QUANTUM; INTERFEROMETER}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, number-of-cited-references = {{17}}, times-cited = {{11}}, journal-iso = {{Phys. Rev. Lett.}}, doc-delivery-number = {{TF684}}, unique-id = {{ISI:A1995TF68400013}} }
@article{ISI:A1995RH41800004, author = {JEX, I and TORMA, P and STENHOLM, S}, title = {{MULTIMODE COHERENT STATES}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1995}}, volume = {{42}}, number = {{7}}, pages = {{1377-1386}}, month = {{JUL}}, abstract = {{We define multimode (entangled) coherent states as properly chosen linear superpositions of suitable composition states. Our definition is equivalent to the definition of coherent states as eigenvectors of a corresponding generalized annihilation operator. In certain limit cases we discuss the statistical properties of the states defined.}}, publisher = {{TAYLOR \& FRANCIS LTD LONDON}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), HELSINKI UNIV,THEORET PHYS RES INST,POB 9,SILTAVUORENPENGER 20 C,SF-00014 HELSINKI,FINLAND. SLOVAK ACAD SCI,INST PHYS,BRATISLAVA 84228,SLOVAKIA.}}, doi = {{10.1080/09500349514551211}}, issn = {{0950-0340}}, keywords-plus = {{PHOTON STATISTICS; SUPERPOSITION; GENERATION}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Torma, Paivi/E-7359-2012}}, number-of-cited-references = {{20}}, times-cited = {{13}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{RH418}}, unique-id = {{ISI:A1995RH41800004}} }
@article{ISI:A1995QZ35600018, author = {JEX, I and STENHOLM, S and ZEILINGER, A}, title = {{HAMILTONIAN THEORY OF A SYMMETRICAL MULTIPORT}}, journal = {{OPTICS COMMUNICATIONS}}, year = {{1995}}, volume = {{117}}, number = {{1-2}}, pages = {{95-101}}, month = {{MAY 15}}, abstract = {{We analyze a simple Hamiltonian model for a passive multiport. We show that such a model can be made symmetric with respect to the outputs for certain (interaction) times up to a certain number of input-output ports. The limit of infinitely many input-output channels is discussed.}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), UNIV HELSINKI, INST THEORET PHYS, POB 9, SILTAVUORENPENGER 20B, SF-00017 HELSINKI, FINLAND. UNIV INNSBRUCK, INST EXPTL PHYS, A-6020 INNSBRUCK, AUSTRIA. SLOVAK ACAD SCI, INST PHYS, CS-84228 BRATISLAVA, SLOVAKIA.}}, doi = {{10.1016/0030-4018(95)00078-M}}, issn = {{0030-4018}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{10}}, times-cited = {{37}}, journal-iso = {{Opt. Commun.}}, doc-delivery-number = {{QZ356}}, unique-id = {{ISI:A1995QZ35600018}} }
@inproceedings{ISI:A1995BE62U00015, author = {Bandilla, A and Drobny, G and Jex, I}, editor = {{Betak, E}}, title = {{Three-wave mixing with entangled and disentangled states}}, booktitle = {{ACTA PHYSICA SLOVACA, VOL 45, NO 3, JUNE 1995}}, year = {{1995}}, pages = {{335-340}}, note = {{3rd Central-European Workshop on Quantum Optics, BUDMERICE CASTLE, SLOVAKIA, APR 28-MAY 01, 1995}}, publisher = {{SLOVAK ACADEMY SCIENCES INSTITUTE PHYSICS}}, address = {{DUBRAVSKA CESTA 9, 842 28 BRATISLAVA, SLOVAKIA}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,D-12484 BERLIN,GERMANY.}}, research-areas = {{Mechanics; Optics; Physics}}, web-of-science-categories = {{Mechanics; Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{0}}, times-cited = {{0}}, doc-delivery-number = {{BE62U}}, unique-id = {{ISI:A1995BE62U00015}} }
@inproceedings{ISI:A1995BE62U00017, author = {Drobny, G and Jex, I}, editor = {{Betak, E}}, title = {{Field state manipulation using a multiatomic system}}, booktitle = {{ACTA PHYSICA SLOVACA, VOL 45, NO 3, JUNE 1995}}, year = {{1995}}, pages = {{347-351}}, note = {{3rd Central-European Workshop on Quantum Optics, BUDMERICE CASTLE, SLOVAKIA, APR 28-MAY 01, 1995}}, publisher = {{SLOVAK ACADEMY SCIENCES INSTITUTE PHYSICS}}, address = {{DUBRAVSKA CESTA 9, 842 28 BRATISLAVA, SLOVAKIA}}, type = {{Proceedings Paper}}, language = {{English}}, affiliation = {{SAS,INST PHYS,BRATISLAVA 84225,SLOVAKIA.}}, research-areas = {{Mechanics; Optics; Physics}}, web-of-science-categories = {{Mechanics; Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{0}}, times-cited = {{0}}, doc-delivery-number = {{BE62U}}, unique-id = {{ISI:A1995BE62U00017}} }
@article{ISI:A1994QD47300006, author = {JEX, I and ORLOWSKI, A}, title = {{WEHRLS ENTROPY DYNAMICS IN A KERR-LIKE MEDIUM}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1994}}, volume = {{41}}, number = {{12}}, pages = {{2301-2306}}, month = {{DEC}}, abstract = {{We report on the time evolution of the Wehrl entropy in a Kerr-like medium. We show that the Wehrl entropy gives a clear signature for the formation of finite superpositions of coherent states (cat-like states). In addition, the actual value of the Wehrl entropy at the time of a superposition formation gives the number of coherent components taking part in the superposition.}}, publisher = {{TAYLOR \& FRANCIS LTD LONDON}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASSISCHE STRAHLUNG,RUDOWER CHAUSSEE 5,D-12489 BERLIN,GERMANY. POLISH ACAD SCI,INST FIZ,PL-02668 WARSAW,POLAND.}}, doi = {{10.1080/09500349414552151}}, issn = {{0950-0340}}, keywords-plus = {{SCHRODINGER-CAT STATES; JAYNES-CUMMINGS MODEL; QUANTUM STATES; SUPERPOSITIONS}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, researcherid-numbers = {{Orlowski, Arkadiusz/A-6443-2008}}, number-of-cited-references = {{23}}, times-cited = {{25}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{QD473}}, unique-id = {{ISI:A1994QD47300006}} }
@article{ISI:A1994PM52700003, author = {DROBNY, G and JEX, I}, title = {{NONDEGENERATE 2-PHOTON DOWN-CONVERSION - COHERENT INPUTS AND NONCLASSICAL EFFECTS}}, journal = {{CZECHOSLOVAK JOURNAL OF PHYSICS}}, year = {{1994}}, volume = {{44}}, number = {{9}}, pages = {{827-842}}, month = {{SEP}}, abstract = {{We study the nondegenerate two-photon down conversion described by a quantum trilinear Hamiltonian. The idler mode is initially prepared in the vacuum while the pump (laser) and the signal mode are prepared in coherent states which at high intensities resemble classical inputs. Such setup with a coherent signal mode allows us to scan the dynamics from the regime of the down conversion (empty signal) up to the frequency conversion (highly excited signal). The analysis concentrates on the entanglement properties of the modes which are compared with their other statistical properties such as squeezing and antibunching to give a more complete characterization of the modes. We show that the single mode nonclassical effects (squeezing and antibunching) disappear when an initial signal intensity highly exceeds that of the pump. In this regime the numerical results are confirmed by approximate analytical calculations. We point out that initially comparable intensities of the signal and pump mode lead to the effect of the `'spontaneous disentanglement'' of the signal mode from others and to the production of its squeezed and sub-Poissonian state which is pure to a good approximation.}}, publisher = {{CZECHOSLOVAK JNL OF PHYSICS}}, address = {{FYZIKALNI USTAV AV NA SLOVANCE 2, PRAGUE, CZECH REPUBLIC 180 40}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,SLOVAKIA. HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASSICHE STRAHLUNG,O-1199 BERLIN,GERMANY.}}, doi = {{10.1007/BF01787791}}, issn = {{0011-4626}}, keywords-plus = {{JAYNES-CUMMINGS MODEL; DOWN-CONVERSION; PUMP; ENTANGLEMENT; ENTROPY; STATES; FLUCTUATIONS; RESONANCE; COLLAPSE; REVIVAL}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, number-of-cited-references = {{25}}, times-cited = {{4}}, journal-iso = {{Czech. J. Phys.}}, doc-delivery-number = {{PM527}}, unique-id = {{ISI:A1994PM52700003}} }
@article{ISI:A1994NA92000010, author = {LEONHARDT, U and JEX, I}, title = {{WIGNER FUNCTIONS AND QUADRATURE DISTRIBUTIONS FOR QUANTUM-OSCILLATOR STATES WITH RANDOM-PHASE}}, journal = {{PHYSICAL REVIEW A}}, year = {{1994}}, volume = {{49}}, number = {{3}}, pages = {{R1555-R1557}}, month = {{MAR}}, abstract = {{Applying a result of Vogel and Risken {[}Phys. Rev. A 40, 2847 (1989)] to quantum-oscillator states with random phase, we found surprisingly simple integral relations between the Wiper function and the quadrature distribution. In particular, we have shown that the balance of increasing and decreasing sections of the quadrature distribution decides the sign of the Wiper function.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Note}}, language = {{English}}, affiliation = {{LEONHARDT, U (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASSISCHE STRAHLUNG,RUDOWER CHAUSSEE 5,D-12484 BERLIN,GERMANY.}}, issn = {{1050-2947}}, keywords-plus = {{HOMODYNE; NOISE}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{19}}, times-cited = {{16}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{NA920}}, unique-id = {{ISI:A1994NA92000010}} }
@article{ISI:A1994MT25800082, author = {DROBNY, G and GANTSOG, T and JEX, I}, title = {{PHASE PROPERTIES OF A FIELD MODE INTERACTING WITH N 2-LEVEL ATOMS}}, journal = {{PHYSICAL REVIEW A}}, year = {{1994}}, volume = {{49}}, number = {{1}}, pages = {{622-625}}, month = {{JAN}}, abstract = {{We analyze the phase properties of a strong cavity field interacting with an ensemble of initially excited N two-level atoms. Using the Pegg-Barnett phase formalism {[}Phys. Rev. A 39, 1665 (1989)], we calculate the phase probability distribution as well as the phase variance. The phase probability density exhibits a (N + 1)-peak structure at the initial stages of the evolution. The phase variance is used to illustrate the progressive randomization of the phase on the long-time evolution. The difference in the phase dynamics for the N even and the N odd case is pointed out.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Note}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,SLOVAKIA. MONGOLIAN STATE UNIV,DEPT THEORET PHYS,ULAANBAATAR 210646,MONGOL PEO REP. HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,D-12484 BERLIN,GERMANY.}}, doi = {{10.1103/PhysRevA.49.622}}, issn = {{1050-2947}}, keywords-plus = {{JAYNES-CUMMINGS MODEL; SPONTANEOUS EMISSION; SUPER-RADIANCE; 2-LEVEL ATOMS; CAVITY; MASER; SYSTEM; EVOLUTION; RADIATION; STATE}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{29}}, times-cited = {{7}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{MT258}}, unique-id = {{ISI:A1994MT25800082}} }
@article{ISI:A1993MN28100010, author = {JEX, I and PAUL, H}, title = {{LONG-TIME BEHAVIOR OF THE FIELD IN A LOSSLESS MICROMASER WITH INTENSITY-DEPENDENT COUPLING-CONSTANT}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1993}}, volume = {{40}}, number = {{12}}, pages = {{2399-2406}}, month = {{DEC}}, abstract = {{Using the asymptotic form of the density matrix the role of the nondiagonal elements of the density matrix is estimated in the lossless micromaser model based on the Jaynes-Cummings model with intensity dependent coupling constant. It is shown that a certain type of a (almost pure) multiphoton state can be generated in this system.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,RUDOWER CHAUSEE 5,D-12484 BERLIN,GERMANY.}}, doi = {{10.1080/09500349314552421}}, issn = {{0950-0340}}, keywords-plus = {{JAYNES-CUMMINGS MODEL; MICROSCOPIC MASER; COHERENT STATES; 2-LEVEL ATOM; QUANTUM; EVOLUTION; REVIVAL; SUPERPOSITIONS; DISSIPATION; GENERATION}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{29}}, times-cited = {{3}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{MN281}}, unique-id = {{ISI:A1993MN28100010}} }
@article{ISI:A1993MF23900002, author = {JEX, I and MATSUOKA, M and KOASHI, M}, title = {{PHASE OF THE FIELD IN THE INTERACTION WITH 2 2-LEVEL ATOMS}}, journal = {{QUANTUM OPTICS}}, year = {{1993}}, volume = {{5}}, number = {{5}}, pages = {{275-286}}, month = {{OCT}}, abstract = {{We present phase properties of a field mode interacting with two two-level atoms using the Pegg and Barnett formalism. We derive analytical and approximate expressions for the phase probability distribution, and calculate the mean value of the phase and their fluctuations. A discussion with respect to the coupling constant of the atoms is given.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), UNIV TOKYO,INST SOLID STATE PHYS,7-22-1 ROPPONGI,MINATO KU,TOKYO 106,JAPAN.}}, doi = {{10.1088/0954-8998/5/5/002}}, issn = {{0954-8998}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, number-of-cited-references = {{0}}, times-cited = {{13}}, doc-delivery-number = {{MF239}}, unique-id = {{ISI:A1993MF23900002}} }
@article{ISI:A1993LW01700024, author = {DROBNY, G and JEX, I}, title = {{THE SYSTEM OF N 2-LEVEL ATOMS INTERACTING WITH A FIELD MODE - ENTANGLEMENT AND PARAMETRIC APPROXIMATION}}, journal = {{OPTICS COMMUNICATIONS}}, year = {{1993}}, volume = {{102}}, number = {{1-2}}, pages = {{141-154}}, month = {{SEP 15}}, abstract = {{We study the entanglement of the cavity field mode to the ensemble of two-level atoms when their interaction is ruled by the Dicke model. Our investigation is focused mainly on initial states with fully excited atomic system and an intense cavity field mode. We give an analysis of the entanglement on the short as well as the long time scale. We derive limit expressions for the entanglement for the first moments of the evolution where the entanglement reaches constant value. We show that in the early moments of the evolution an almost pure state can be generated under suitable conditions when the intensity of the field is approximately N. On the long time scale we point out the appearance of a clear decrease of the entanglement associated with the collapse-revival phenomenon of the mean photon number in this model. The bifurcation of initially a gaussian Q-function of the field mode into N + 1 peaks of different weight factors is shown. Finally the results known for the Jaynes-Cummings model are compared with the obtained results.}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA. HUMBOLDT UNIV BERLIN,MAX PLANCK GESELLS,ARBEITSGRP NICHTKLASSISCHE STRAHLUNG,O-1199 BERLIN,GERMANY.}}, doi = {{10.1016/0030-4018(93)90485-N}}, issn = {{0030-4018}}, keywords-plus = {{JAYNES-CUMMINGS MODEL; SPONTANEOUS EMISSION; STATE; RESONANCE; COLLAPSE; ENTROPY; REVIVAL}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{24}}, times-cited = {{20}}, journal-iso = {{Opt. Commun.}}, doc-delivery-number = {{LW017}}, unique-id = {{ISI:A1993LW01700024}} }
@article{ISI:A1993LW83800013, author = {JEX, I}, title = {{REVIVAL TIME-ESTIMATION IN THE PROCESS OF DOWN-CONVERSION}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1993}}, volume = {{40}}, number = {{9}}, pages = {{1753-1761}}, month = {{SEP}}, abstract = {{We analyse the collapse-revival phenomenon in the process of k-photon down conversion with quantized pump for initial Fock states. We give an explanation for the appearance of the revivals by analysing the decomposition of the initial state into the interaction Hamiltonian eigenvectors. A quantitative estimation of the revival times is given as well.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), HUMBOLDT UNIV BERLIN,MAX PLANCK GESELL,ARBEITSGRP NICHTKLASS STRAHLUNG,RUDOWER CHAUSSEE 5,O-1199 BERLIN,GERMANY.}}, doi = {{10.1080/09500349314551771}}, issn = {{0950-0340}}, keywords-plus = {{COHERENT STATES; K-PHOTON; COLLAPSE; ATOM; CAVITY; LIGHT; MODEL}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{24}}, times-cited = {{3}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{LW838}}, unique-id = {{ISI:A1993LW83800013}} }
@article{ISI:A1993LW84500004, author = {DROBNY, G and JEX, I}, title = {{2-MODE SU(2) COHERENT STATES FOR KAPPA-PHOTON DOWN-CONVERSION PROCESS WITH QUANTIZED PUMP}}, journal = {{CZECHOSLOVAK JOURNAL OF PHYSICS}}, year = {{1993}}, volume = {{43}}, number = {{8}}, pages = {{797-806}}, month = {{AUG}}, abstract = {{We analyze the statistical properties of the two-mode SU(2) coherent states associated with the process of k-photon down conversion with quantized pump. We show that the modes exhibit sub-Poissonian photon statistics, anticorrelation and in some particular cases also squeezing. The influence of various initial number states on this effects is analyzed in detail.}}, publisher = {{CZECHOSLOVAK JNL OF PHYSICS}}, address = {{FYZIKALNI USTAV AV NA SLOVANCE 2, PRAGUE, CZECH REPUBLIC 180 40}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, doi = {{10.1007/BF01589801}}, issn = {{0011-4626}}, keywords-plus = {{FLUCTUATIONS; LIGHT}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, number-of-cited-references = {{28}}, times-cited = {{0}}, journal-iso = {{Czech. J. Phys.}}, doc-delivery-number = {{LW845}}, unique-id = {{ISI:A1993LW84500004}} }
@article{ISI:A1993LM34100076, author = {DROBNY, G and JEX, I and BUZEK, V}, title = {{MODE ENTANGLEMENT IN NONDEGENERATE DOWN-CONVERSION WITH QUANTIZED PUMP}}, journal = {{PHYSICAL REVIEW A}}, year = {{1993}}, volume = {{48}}, number = {{1}}, pages = {{569-579}}, month = {{JUL}}, abstract = {{We study entanglement between field modes in the process of nondegenerate two-photon down-conversion with quantized pump. We show that due to the quantum nature of the dynamics, strong entanglement between the pump and the signal-idler subsystems can be observed. We find that the higher the initial intensity of the pump mode the stronger the entanglement between the pump and the signal-idler subsystem is established during the first instants of the time evolution. We also show that the signal and the idler modes are strongly entangled (correlated). This entanglement is much stronger than the entanglement between the pump and the signal-idler subsystem. Correlation between the signal and the idler modes leads to a high degree of two-mode squeezing, which can be observed during the first instants of the time evolution when the pump mode is still approximately in a pure state. On the other hand, the back action of the signal-idler subsystem on the pump mode leads to a strong single-mode squeezing of the pump mode. At the time interval during which squeezing of the pump mode can be observed the pump mode is far from being in the minimum uncertainty state. We also analyze the longtime behavior of the quantum-optical system under consideration and we show that the interesting collapse-revival effect in the time evolution of the mean photon number and of the purity parameters of field modes can be observed. Finally, we show that the degree of entanglement between modes in the nondegenerate quantum-optical down-conversion strongly depends on the initial state of the system.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA. WEIZMANN INST SCI,DEPT CHEM PHYS,IL-76100 REHOVOT,ISRAEL.}}, doi = {{10.1103/PhysRevA.48.569}}, issn = {{1050-2947}}, keywords-plus = {{ENTROPY; STATES; GENERATION; PHOTON}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{25}}, times-cited = {{32}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{LM341}}, unique-id = {{ISI:A1993LM34100076}} }
@article{ISI:A1993LG39900003, author = {JEX, I and BUZEK, V}, title = {{MULTIPHOTON COHERENT STATES AND THE LINEAR SUPERPOSITION PRINCIPLE}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1993}}, volume = {{40}}, number = {{5}}, pages = {{771-783}}, month = {{MAY}}, abstract = {{We show that multiphoton coherent states can be expressed as linear quantum superpositions of a finite number of generalized coherent states. Quantum interferences between component states lead to appearance of non-classical effects such as oscillations in the photon number distribution, quadrature squeezing, SU(1, 1) squeezing and others.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), SLOVAK ACAD SCI, INST PHYS, DUBRAVSKA CESTA 9, CS-84228 BRATISLAVA, CZECHOSLOVAKIA.}}, doi = {{10.1080/09500349314550811}}, issn = {{0950-0340}}, keywords-plus = {{JAYNES-CUMMINGS MODEL; SQUEEZED STATES; FIELD; FLUCTUATIONS; EXPANSION; RESONANCE; EVOLUTION; ENTROPY; PHASE}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{53}}, times-cited = {{27}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{LG399}}, unique-id = {{ISI:A1993LG39900003}} }
@article{ISI:A1993KW30900055, author = {JEX, I and DROBNY, G}, title = {{PHASE PROPERTIES AND ENTANGLEMENT OF THE FIELD MODES IN A 2-MODE COUPLER WITH INTENSITY-DEPENDENT COUPLING}}, journal = {{PHYSICAL REVIEW A}}, year = {{1993}}, volume = {{47}}, number = {{4, B}}, pages = {{3251-3258}}, month = {{APR}}, abstract = {{We study the phase properties of two quantized modes within the model of a two-mode coupler with intensity-dependent coupling. The dynamics of the system is solved numerically as an approximate analytical solution is available only for the initial moments of the time evolution. The phase properties are discussed on the basis of the joint phase distribution. Other quantities of the particular modes (measure of entropy and photon-number distribution) are presented to support the conclusions reached on the basis of the joint phase distribution. The obtained results are compared with the known results for the closely related model of an ordinary linear coupler.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), UNIV TOKYO,INST SOLID STATE PHYS,7-22-1 ROPPONGI,MINATO KU,TOKYO 106,JAPAN. SLOVAK ACAD SCI,INST PHYS,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, doi = {{10.1103/PhysRevA.47.3251}}, issn = {{1050-2947}}, keywords-plus = {{COHERENT STATES; QUANTUM-OPTICS; PERIODIC DECAY; FLUCTUATIONS; CONVERSION; ENTROPY; OPERATOR; SYSTEMS; REVIVAL; SU(2)}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{30}}, times-cited = {{8}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{KW309}}, unique-id = {{ISI:A1993KW30900055}} }
@inproceedings{ISI:A1993BZ07F00034, author = {BUZEK, V and DROBNY, G and JEX, I}, editor = {{Akos, G and Lippenyi, T and Lupkovics, G and Podmaniczky, A}}, title = {{SIGNAL-PUMP ENTANGLEMENT IN QUANTUM-OPTICAL PROCESSES}}, booktitle = {{16TH CONGRESS OF THE INTERNATIONAL COMMISSION FOR OPTICS : OPTICS AS A KEY TO HIGH TECHNOLOGY, PTS 1 AND 2}}, series = {{PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE)}}, year = {{1993}}, volume = {{1983}}, pages = {{90-91}}, note = {{16TH CONGRESS OF THE INTERNATIONAL-COMMISSION-FOR-OPTICS : OPTICS AS A KEY TO HIGH TECHNOLOGY ( ICO-16 ), BUDAPEST, HUNGARY, AUG 09-13, 1993}}, organization = {{INT COMMISS OPT; SCI SOC OPT ACOUST \& FILMTECH; SOC PHOTO OPT INSTRUMENTAT ENGINEERS; OPT SOC AMER; EUROPEAN OPT SOC; HUNGARIAN NATL COMM TECHNOL DEV; INT UNION PURE \& APPL PHYS; HUNGARIAN OPT WORKS; LASRAM LASER TECHNOL}}, publisher = {{SPIE - INT SOC OPTICAL ENGINEERING}}, address = {{BELLINGHAM}}, type = {{Proceedings Paper}}, language = {{English}}, isbn = {{0-8194-1230-9}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{0}}, times-cited = {{0}}, doc-delivery-number = {{BZ07F}}, unique-id = {{ISI:A1993BZ07F00034}} }
@article{ISI:A1992KB79400021, author = {JEX, I and DROBNY, G and MATSUOKA, M}, title = {{QUANTUM PHASE PROPERTIES OF THE PROCESS OF KAPPA-PHOTON DOWN CONVERSION WITH QUANTIZED PUMP}}, journal = {{OPTICS COMMUNICATIONS}}, year = {{1992}}, volume = {{94}}, number = {{6}}, pages = {{619-627}}, month = {{DEC 15}}, abstract = {{We study the phase properties of the field modes in the process of k-photon down conversion with quantized pump using the Peggy-Barnett phase formalism. The dynamics of the system is solved numerically via the diagonalization of the interaction hamiltonian. The behavior in the short and long time limit is discussed and compared to previous results related to the treated problem. In order to understand our results an exactly soluble model of the linearized k-photon down conversion is presented.}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), UNIV TOKYO,INST SOLID STATE PHYS,7-22-1 ROPPONGI,MINATO KU,TOKYO 106,JAPAN. SLOVAK ACAD SCI,INST PHYS,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, doi = {{10.1016/0030-4018(92)90611-T}}, issn = {{0030-4018}}, keywords-plus = {{PARAMETRIC DOWN-CONVERSION; SQUEEZED COHERENT STATES; LIGHT; FLUCTUATIONS; OPERATOR}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{34}}, times-cited = {{4}}, journal-iso = {{Opt. Commun.}}, doc-delivery-number = {{KB794}}, unique-id = {{ISI:A1992KB79400021}} }
@article{ISI:A1992KB65800008, author = {DROBNY, G and JEX, I and MATSUOKA, M}, title = {{COLLAPSE REVIVAL PHENOMENON IN THE PROCESS OF K-PHOTON DOWN CONVERSION WITH SUPERPOSITIONS OF NUMBER STATES}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1992}}, volume = {{39}}, number = {{11}}, pages = {{2229-2243}}, month = {{NOV}}, abstract = {{We calculate numerically the time evolution of the mean photon number in the process of k-photon down conversion process with quantized pump. The pump mode was supposed to be initially in a superposition of number states and the down converted mode in a number state. We analysed in some detail the influence of the initial field statistics of the pump mode as well as the presence of non-vacuum number states in the down converted mode on the appearance of collapses and revivals.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SAS,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA. UNIV TOKYO,INST SOLID STATE PHYS,MINATO KU,TOKYO 106,JAPAN.}}, doi = {{10.1080/09500349214552261}}, issn = {{0950-0340}}, keywords-plus = {{SQUEEZED COHERENT STATES; JAYNES-CUMMINGS MODEL; MINIMUM-UNCERTAINTY PACKETS; HARMONIC-GENERATION; EQUIVALENCE CLASSES; QUANTUM-OPTICS; 2-LEVEL ATOM; LIGHT; FIELD; CAVITY}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{45}}, times-cited = {{2}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{KB658}}, unique-id = {{ISI:A1992KB65800008}} }
@article{ISI:A1992JQ00100010, author = {DROBNY, G and JEX, I}, title = {{PHASE PROPERTIES OF FIELD MODES IN THE PROCESS OF KTH HARMONIC-GENERATION}}, journal = {{PHYSICS LETTERS A}}, year = {{1992}}, volume = {{169}}, number = {{4}}, pages = {{273-280}}, month = {{SEP 28}}, abstract = {{We study the phase properties of the two field modes within the frame of the process of kth harmonic generation with a quantized fundamental mode. Using the Pegg-Barnett phase formalism the joint phase distribution is calculated numerically. It is shown that in the initial moments of the evolution the degree of the process k does not affect significantly the phase distribution.}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA. UNIV TOKYO,INST SOLID STATE PHYS,MINATO KU,TOKYO 106,JAPAN.}}, doi = {{10.1016/0375-9601(92)90458-X}}, issn = {{0375-9601}}, keywords-plus = {{FLUCTUATIONS; CONVERSION; OPERATOR; STATES; LIGHT}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, number-of-cited-references = {{21}}, times-cited = {{3}}, journal-iso = {{Phys. Lett. A}}, doc-delivery-number = {{JQ001}}, unique-id = {{ISI:A1992JQ00100010}} }
@article{ISI:A1992JC55800066, author = {DROBNY, G and JEX, I}, title = {{QUANTUM-PROPERTIES OF FIELD MODES IN TRILINEAR OPTICAL PROCESSES}}, journal = {{PHYSICAL REVIEW A}}, year = {{1992}}, volume = {{46}}, number = {{1}}, pages = {{499-506}}, month = {{JUL 1}}, abstract = {{We consider a trilinear Hamiltonian in boson operators describing various physical processes such as frequency conversion, Raman or Brillouin scattering, or the interaction of N two-level atoms with a single-mode radiation field. Due to the fact that two independent integrals of motion can be found, the solution of the dynamics of the system is reduced to the diagonalization of a finite matrix (as was already shown by Walls and Barakat {[}Phys. Rev. A 1, 446 (1970)]). Performing a numerical diagonalization, we analyze the statistical properties of the field modes (sub-Poissonian statistics, anticorrelation, squeezing). We also pay attention to the appearance of collapses and revivals in the mean photon number of the modes. The relation of this model to the model of two coupled modes with an intensity-dependent coupling constant is pointed out.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA. UNIV TOKYO,INST SOLID STATE PHYS,TOKYO 106,JAPAN.}}, doi = {{10.1103/PhysRevA.46.499}}, issn = {{1050-2947}}, keywords-plus = {{JAYNES-CUMMINGS MODEL; RADIATION-FIELD; COHERENT STATES; PERIODIC DECAY; STATISTICS; REVIVAL; DYNAMICS; SU(2)}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{37}}, times-cited = {{36}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{JC558}}, unique-id = {{ISI:A1992JC55800066}} }
@article{ISI:A1992HY06200013, author = {JEX, I and DROBNY, G}, title = {{SU(1,1) AND SU(2) SQUEEZING IN TRILINEAR OPTICAL PROCESSES}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1992}}, volume = {{39}}, number = {{5}}, pages = {{1043-1053}}, month = {{MAY}}, abstract = {{The squeezing properties in terms of SU(1, 1) and SU(2) operators for the case of trilinear processes are studied. The initial state of the system is supposed to be a coherent state in one of the modes and number states in the remaining modes. It is pointed out that in several cases a considerable amount of squeezing can be achieved. Due to the common mathematical structure the case of a two-mode coupler with intensity dependent coupling is also analysed.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), UNIV TOKYO,INST SOLID STATE PHYS,MINATO KU,TOKYO 106,JAPAN. SLOVAK ACAD SCI,INST PHYS,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, doi = {{10.1080/09500349214551061}}, issn = {{0950-0340}}, keywords-plus = {{COHERENT STATES; ELECTROMAGNETIC-FIELD; RADIATION-FIELD; QUANTUM-OPTICS; PERIODIC DECAY; DYNAMICS; ATOM; STATISTICS; AMPLITUDE; REVIVAL}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{39}}, times-cited = {{5}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{HY062}}, unique-id = {{ISI:A1992HY06200013}} }
@article{ISI:A1992HT68400017, author = {JEX, I}, title = {{EMISSION-SPECTRA OF A 2-LEVEL ATOM UNDER THE PRESENCE OF ANOTHER 2-LEVEL ATOM}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1992}}, volume = {{39}}, number = {{4}}, pages = {{835-844}}, month = {{APR}}, abstract = {{We investigate the spectrum of light emitted by a two-level atom interacting with another two-level atom inside an ideal cavity within the frame of generalized Jaynes-Cummings model. The influence of various ratios of the coupling constants of the atoms to the field on the spectrum of the emitted light is studied in detail for the case when the atoms are supposed to be initially in the excited state and the field in a Fock state as well as their superposition.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{JEX, I (Reprint Author), UNIV TOKYO,INST SOLID STATE PHYS,MINATO KU,TOKYO 106,JAPAN.}}, doi = {{10.1080/09500349214550831}}, issn = {{0950-0340}}, keywords-plus = {{JAYNES-CUMMINGS MODEL; RABI OSCILLATIONS; SQUEEZED VACUUM; N ATOMS; CAVITY; STATES; LIGHT}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{35}}, times-cited = {{0}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{HT684}}, unique-id = {{ISI:A1992HT68400017}} }
@article{ISI:A1992HN47600011, author = {DROBNY, G and JEX, I}, title = {{STATISTICS OF FIELD MODES IN THE PROCESS OF KAPPA-PHOTON DOWN-CONVERSION WITH A QUANTIZED PUMP}}, journal = {{PHYSICAL REVIEW A}}, year = {{1992}}, volume = {{45}}, number = {{7, B}}, pages = {{4897-4903}}, month = {{APR 1}}, abstract = {{We solve numerically the dynamics of a system related to the problem of k-photon down-conversion with a quantized pump. We analyze in detail the statistical properties of the field modes. We show that the fields exhibit sub-Poissonian statistics and anticorrelation. The influence of different initial Fock states as well as their coherent superpositions on the field statistics and squeezing of the modes is analyzed in detail.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA. UNIV TOKYO,INST SOLID STATE PHYS,MINATO KU,TOKYO 106,JAPAN.}}, doi = {{10.1103/PhysRevA.45.4897}}, issn = {{1050-2947}}, keywords-plus = {{SQUEEZED COHERENT STATES; LIGHT; SU(2)}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{19}}, times-cited = {{16}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{HN476}}, unique-id = {{ISI:A1992HN47600011}} }
@article{ISI:A1992HC99500065, author = {DROBNY, G and JEX, I}, title = {{COLLAPSES AND REVIVALS IN THE ENERGY EXCHANGE IN THE PROCESS OF KAPPA-PHOTON DOWN-CONVERSION WITH QUANTIZED PUMP}}, journal = {{PHYSICAL REVIEW A}}, year = {{1992}}, volume = {{45}}, number = {{3}}, pages = {{1816-1821}}, month = {{FEB 1}}, abstract = {{We analyze the collapse and revival phenomenon in the energy exchange of two field modes initially prepared in a Fock state, as well as their coherent superposition in the process of k-photon down-conversion with quantized pump. The influence of the presence of a Kerr-like medium is discussed.}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Article}}, language = {{English}}, affiliation = {{DROBNY, G (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA. UNIV TOKYO,INST SOLID STATE PHYS,MINATO KU,TOKYO 106,JAPAN.}}, doi = {{10.1103/PhysRevA.45.1816}}, issn = {{1050-2947}}, keywords-plus = {{COHERENT STATES; QUANTUM-OPTICS; ATOM; RADIATION; CAVITY; FIELD; MODEL}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{25}}, times-cited = {{23}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{HC995}}, unique-id = {{ISI:A1992HC99500065}} }
@article{ISI:A1992HG44500002, author = {BERNAT, V and JEX, I}, title = {{QUANTUM COLLAPSE AND REVIVAL OF A 2-LEVEL ATOM WITH INTENSITY-DEPENDENT DETUNING IN A FINITE Q-CAVITY AT FINITE TEMPERATURE}}, journal = {{QUANTUM OPTICS}}, year = {{1992}}, volume = {{4}}, number = {{1}}, pages = {{9-17}}, month = {{FEB}}, abstract = {{We consider a generalization of the Jaynes-Cummings model when the cavity is supposed to be filled with a Kerr-like medium. This non-linearity induced by the Kerr-like medium leads to an inhibited decay of the initially excited atom. In the present paper we analyse the influence of the quality of the cavity and the influence of a thermofield on the collapses and revivals of the atomic inversion.}}, publisher = {{IOP PUBLISHING LTD}}, address = {{TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX}}, type = {{Article}}, language = {{English}}, affiliation = {{BERNAT, V (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84238 BRATISLAVA,CZECHOSLOVAKIA.}}, doi = {{10.1088/0954-8998/4/1/002}}, issn = {{0954-8998}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Applied}}, number-of-cited-references = {{0}}, times-cited = {{5}}, doc-delivery-number = {{HG445}}, unique-id = {{ISI:A1992HG44500002}} }
@article{ISI:A1991FM47500017, author = {BUZEK, V and JEX, I}, title = {{EMISSION-SPECTRA OF A 2-LEVEL ATOM IN A KERR-LIKE MEDIUM}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1991}}, volume = {{38}}, number = {{5}}, pages = {{987-996}}, month = {{MAY}}, abstract = {{We have investigated the spectrum of light emitted by a single atom interacting with a single mode of the radiation field in an ideal cavity filled with a Kerr-like medium. It is shown that owing to the Kerr-like nonlinearity in the system the spectrum of the emitted light exhibits a single-peaked structure for sufficiently high intensities of the initial coherent field instead of the triplet structure in the case of the standard Jaynes-Cummings model.}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{BUZEK, V (Reprint Author), UNIV LONDON IMPERIAL COLL SCI \& TECHNOL,BLACKETT LAB,OPT SECT,LONDON SW7 2BZ,ENGLAND. SLOVAK ACAD SCI,INST PHYS,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, doi = {{10.1080/09500349114550961}}, issn = {{0950-0340}}, keywords-plus = {{JAYNES-CUMMINGS MODEL; INHIBITED SPONTANEOUS EMISSION; SIMPLE QUANTUM MODEL; RABI OSCILLATIONS; SQUEEZED VACUUM; CAVITY; REVIVAL; COLLAPSE; ABSORPTION; RESONANCE}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{44}}, times-cited = {{16}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{FM475}}, unique-id = {{ISI:A1991FM47500017}} }
@article{ISI:A1991FH65200003, author = {BUZEK, V and JEX, I and BRISUDOVA, M}, title = {{JAYNES-CUMMINGS MODEL WITH DISPLACED NUMBER STATES}}, journal = {{INTERNATIONAL JOURNAL OF MODERN PHYSICS B}}, year = {{1991}}, volume = {{5}}, number = {{5}}, pages = {{797-814}}, month = {{MAR}}, abstract = {{We investigate the dynamics of the Jaynes-Cummings model with the cavity field initially prepared in the displaced number state. The time evolution of the atomic population inversion, squeezing of the cavity field and the emission spectra from the two-level atom are studied.}}, publisher = {{WORLD SCIENTIFIC PUBL CO PTE LTD}}, address = {{JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 9128, SINGAPORE}}, type = {{Article}}, language = {{English}}, affiliation = {{BUZEK, V (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, doi = {{10.1142/S0217979291000420}}, issn = {{0217-9792}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Applied; Physics, Condensed Matter; Physics, Mathematical}}, number-of-cited-references = {{0}}, times-cited = {{11}}, journal-iso = {{Int. J. Mod. Phys. B}}, doc-delivery-number = {{FH652}}, unique-id = {{ISI:A1991FH65200003}} }
@article{ISI:A1991FB49200003, author = {BUZEK, V and JEX, I}, title = {{MULTIPHOTON STATES AND AMPLITUDE K-TH POWER SQUEEZING}}, journal = {{NUOVO CIMENTO DELLA SOCIETA ITALIANA DI FISICA B-GENERAL PHYSICS RELATIVITY ASTRONOMY AND MATHEMATICAL PHYSICS AND METHODS}}, year = {{1991}}, volume = {{106}}, number = {{2}}, pages = {{147-157}}, month = {{FEB}}, abstract = {{On the basis of the work of d'Ariano and coworkers we introduce a new type of multiphoton states. We analyse amplitude k-th power squeezing of the multiphoton states. In particular, we show that even if the multiphoton states do not exhibit ordinary squeezing they can be amplitude k-th power squeezed.}}, publisher = {{EDITRICE COMPOSITORI BOLOGNA}}, address = {{VIA STALINGRADO 97/2, I-40128 BOLOGNA, ITALY}}, type = {{Article}}, language = {{English}}, affiliation = {{BUZEK, V (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, issn = {{0369-3554}}, keywords = {{QUANTUM THEORY; QUANTUM MECHANICS; NONCLASSICAL PHOTON STATES (INCLUDING ANTIBUNCHED; SQUEEZED; SUB-POISSONIAN)}}, keywords-plus = {{COHERENT STATES; FIELD; FLUCTUATIONS}}, research-areas = {{Physics}}, web-of-science-categories = {{Physics, Multidisciplinary}}, number-of-cited-references = {{29}}, times-cited = {{3}}, journal-iso = {{Nouvo Cimento Soc. Ital. Fis. B-Gen. Phys. Relativ. Astron. Math. Phys. Methods}}, doc-delivery-number = {{FB492}}, unique-id = {{ISI:A1991FB49200003}} }
@article{ISI:A1990EC68100023, author = {BUZEK, V and JEX, I}, title = {{DYNAMICS OF A 2-LEVEL ATOM IN A KERR-LIKE MEDIUM}}, journal = {{OPTICS COMMUNICATIONS}}, year = {{1990}}, volume = {{78}}, number = {{5-6}}, pages = {{425-435}}, month = {{SEP 15}}, publisher = {{ELSEVIER SCIENCE BV}}, address = {{PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}}, type = {{Article}}, language = {{English}}, affiliation = {{BUZEK, V (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, doi = {{10.1016/0030-4018(90)90340-Y}}, issn = {{0030-4018}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{61}}, times-cited = {{106}}, journal-iso = {{Opt. Commun.}}, doc-delivery-number = {{EC681}}, unique-id = {{ISI:A1990EC68100023}} }
@article{ISI:A1990CY12500080, author = {BUZEK, V and JEX, I}, title = {{AMPLITUDE KAPPA-TH-POWER SQUEEZING OF KAPPA-PHOTON COHERENT STATES}}, journal = {{PHYSICAL REVIEW A}}, year = {{1990}}, volume = {{41}}, number = {{7}}, pages = {{4079-4082}}, month = {{APR 1}}, publisher = {{AMERICAN PHYSICAL SOC}}, address = {{ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}}, type = {{Note}}, language = {{English}}, affiliation = {{BUZEK, V (Reprint Author), SLOVAK ACAD SCI,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, issn = {{1050-2947}}, research-areas = {{Optics; Physics}}, web-of-science-categories = {{Optics; Physics, Atomic, Molecular \& Chemical}}, number-of-cited-references = {{23}}, times-cited = {{17}}, journal-iso = {{Phys. Rev. A}}, doc-delivery-number = {{CY125}}, unique-id = {{ISI:A1990CY12500080}} }
@article{ISI:A1990CH91300003, author = {BUZEK, V and JEX, I and QUANG, T}, title = {{K-PHOTON COHERENT STATES}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1990}}, volume = {{37}}, number = {{2}}, pages = {{159-163}}, month = {{FEB}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Letter}}, language = {{English}}, affiliation = {{BUZEK, V (Reprint Author), EPRC SAS,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA. JOINT INST NUCL RES,MOSCOW 101000,USSR.}}, doi = {{10.1080/09500349014550231}}, issn = {{0950-0340}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{21}}, times-cited = {{52}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{CH913}}, unique-id = {{ISI:A1990CH91300003}} }
@article{ISI:A1989AT46600003, author = {BUZEK, V and JEX, I}, title = {{COLLAPSE REVIVAL PHENOMENON IN THE JAYNES-CUMMINGS MODEL INTERACTING WITH THE MULTIPHOTON HOLSTEIN-PRIMAKOFF SU(2) COHERENT STATE}}, journal = {{JOURNAL OF MODERN OPTICS}}, year = {{1989}}, volume = {{36}}, number = {{11}}, pages = {{1427-1434}}, month = {{NOV}}, publisher = {{TAYLOR \& FRANCIS LTD}}, address = {{ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE}}, type = {{Article}}, language = {{English}}, affiliation = {{BUZEK, V (Reprint Author), SLOVAK ACAD SCI,EPRC,INST PHYS,DUBRAVSKA CESTA 9,CS-84228 BRATISLAVA,CZECHOSLOVAKIA.}}, issn = {{0950-0340}}, research-areas = {{Optics}}, web-of-science-categories = {{Optics}}, number-of-cited-references = {{29}}, times-cited = {{13}}, journal-iso = {{J. Mod. Opt.}}, doc-delivery-number = {{AT466}}, unique-id = {{ISI:A1989AT46600003}} }
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