Quantum dynamics, optics and informatics

For more than a century, quantum mechanics has proven to be the correct theory to describe the physics of the microworld. Part of its charm is that it repeatedly reveals unexpected and fascinating effects. One of the most recent surprises arose from the combination of quantum mechanics, information theory, and simulations, leading to the concept of quantum information theory. The basic idea behind this direction of research is the use of quantum particles as carriers of information. This opens up new possibilities for information processing that are unparalleled in classical computer science.

Our group focuses on research in quantum dynamics, quantum information and quantum optics. We investigate the properties of quantum walks and their applications to simulations of coherent transport of excitations. We are interested in open dynamics, i.e. the evolution of physical systems under the influence of interaction with the environment, and its effect on quantum systems. We also study the evolution of quantum systems under the influence of measurements, which in some cases leads to chaotic dynamics. In the field of quantum information, we focus on search algorithms and state transfer between network nodes. We also address the problem of so-called boson sampling, a classically challenging problem on which the advantages of quantum computers can be studied. Our results have formed the basis of a series of experiments performed by Prof. Silberhorn's group at Paderborn using linear quantum optics. In our research, we work closely with groups in Germany (Paderborn, Darmstadt, Ulm), Hungary (Budapest), the UK (Glasgow), Japan (Yokohama), and Greece (Heraklion).

Members

Staff

Selected publications

• M. Štefaňák and S. Skoupý: Quantum walk state transfer on a hypercube, Phys. Scr. 98, 104003 (2023) [iop]
• J. Novotný, J. Maryška, and I. Jex: Jaynes' principle for quantum Markov processes: generalized Gibbs-von Neumann states rule. Eur. Phys. J. Plus 138, 657 (2023) [arxiv.org, springer]
• M. Štefaňák: Monitored recurrence of a one-parameter family of three-state quantum walks, Phys. Scr. 98, 064001 (2023) [arxiv.org, iop]
• D. Štěrba, J. Novotný and I. Jex: Asymptotic phase-locking and synchronization in two-qubit systems, J. Phys. Commun. 7, 045003 (2023) [iop]
• P.V. Pyshkin, A. Gábris, Da-Wei Luo, J.Q. You, and Lian-Ao Wu: Tunable Tradeoff between Quantum and Classical Computation via Nonunitary Zeno-like Dynamics, Phys. Rev. Applied 18, 044060 (2022) [arxiv.org, aps.org]
• N. Konno, E. Segawa and M. Štefaňák: Relation between Quantum Walks with Tails and Quantum Walks with Sinks on Finite Graphs, Symmetry 13, 1169 (2021) [mdpi]
• J. Novotný, A. Mariano, S. Pascazio, A. Scardicchio, and I. Jex: Relaxation to equilibrium in controlled-not quantum networks, Phys. Rev. A 103, 042218 (2021) [arxiv.org, aps.org]
• G. Karpat, I. Yalçinkaya, B. Çakmak, G. L. Giorgi, and R. Zambrini: Synchronization and non-Markovianity in open quantum systems, Phys. Rev. A 103, 062217 (2021) [aps.org]
• T. Nitsche, S. De, S. Barkhofen, E. Meyer-Scott, J. Tiedau, J. Sperling, A. Gábris, I. Jex, and Ch. Silberhorn: Local Versus Global Two-Photon Interference in Quantum Networks. Phys. Rev. Lett. 125, 213604 (2020) [arxiv.org, aps.org]
• G. Karpat, I. Yalçınkaya, and B. Çakmak: Quantum synchronization of few-body systems under collective dissipation, Phys. Rev. A 101, 042121 (2020) [aps.org]
• J. Mareš, J. Novotný, M. Štefaňák, and I. Jex: Counterintuitive role of geometry in transport by quantum walks. Phys. Rev. A 101, 032113 (2020) [arxiv.org, aps.org]
• R. Kruse, C. S. Hamilton, L. Sansoni, S. Barkhofen, Ch. Silberhorn, and I. Jex: Detailed study of Gaussian boson sampling. Phys. Rev. A 100, 032326 (2019) [arxiv.org, aps.org]
• G. Karpat, I. Yalçınkaya, and B. Çakmak: Quantum synchronization in a collision model, Phys. Rev. A 100, 012133 (2019) [aps.org]
• T. Nitsche, S. Barkhofen, R. Kruse, L. Sansoni, M. Štefaňák, A. Gábris, V. Potoček, T. Kiss, I. Jex and Ch. Silberhorn: Probing measurement-induced effects in quantum walks via recurrence. Science Advances 4, eaar6444 (2018)  [sciencemag.org]
• C. S. Hamilton, R. Kruse, L. Sansoni, S. Barkhofen, Ch. Silberhorn, and Igor Jex: Gaussian Boson Sampling. Phys. Rev. Lett. 119, 170501 (2017) [arxiv, aps.org]

• S. Barkhofen, T. J. Bartley, L. Sansoni, R. Kruse, C. S. Hamilton, I. Jex, and Ch. Silberhorn: Driven Boson Sampling. Phys. Rev. Lett. 118, 020502 (2017). [arviv.org]

• A. Gilyén, T. Kiss, and I. Jex: Exponential Sensitivity and its Cost in Quantum Physics. Scientific Reports 6, 20076 (2016). [nature.com]

• M. Štefaňák, and S. Skoupý: Perfect state transfer by means of discrete-time quantum walk search algorithms on highly symmetric graphs, Phys. Rev. A 94, 022301 (2016). [arxiv.org]

• J. Maryška, J. Novotný, and I. Jex: Dominant couplings in qubit networks with controlled interactions, J. Phys. A 48, 215301 (2015). [arxiv.org]

• M. Štefaňák,  I. Bezděková, and I. Jex: Limit distributions of three-state quantum walks: The role of coin eigenstates, Phys. Rev. A 90, 012342 (2014). [arxiv.org]

• J. Novotný, G. Alber, and I. Jex: Universality in random quantum networks. Phys. Rev. A 92, 062335 (2015). [arxiv.org]

• F. Elster, S. Barkhofen, T. Nitsche, J. Novotný, A. Gábris, I. Jex, and Ch. Silberhorn: Quantum walk coherences on a dynamical percolation graph. Scientific Reports 5, 13495 (2015). [nature.com]

• A. Schreiber, A. Gábris, P. P. Rohde, K. Laiho, M. Štefaňák, V. Potoček, C. Hamilton, I. Jex, and Ch. Silberhorn: A 2D Quantum Walk Simulation of Two-Particle Dynamics. Science 336, 55 (2012). [arxiv.org]

• G. M. Nikolopoulos, A. Hoskovec, and I. Jex: Analysis and minimization of bending losses in discrete quantum networks, Phys. Rev. A 85, 062319 (2012). [arxiv.org]

• T. Kiss, S. Vymetal, L. D. Toth, A. Gabris, I. Jex, and G. Alber: Measurement-Induced Chaos with Entangled States, Phys. Rev. Lett. 107, 100501 (2011). [arxiv.org]

• A. Schreiber, K. N. Cassemiro, V. Potoček, A. Gábris, P. J. Mosley, E. Andersson, I. Jex, and Ch. Silberhorn: Photons Walking the Line: A Quantum Walk with Adjustable Coin Operations. Phys. Rev. Lett. 104, 050502 (2010). [arxiv.org]

• V. Potoček, A. Gábris, T. Kiss, I. Jex: Optimized quantum random-walk search algorithms on the hypercube. Phys. Rev. A 79, 012325 (2009). [arxiv.org]

• M. Štefaňák, I. Jex, and T. Kiss: Recurrence and Polya number of quantum walks, Phys. Rev. Lett. 100, 020501 (2008). [arxiv.org]

More informations and actualities on the page of our Facebook's group.