Group of Many-Body Quantum Theory, Institute of Particle and Nuclear Physics

Our research can be divided into two key areas. The first area is the study of various forms of quantum critical phenomena, in particular quantum phase transitions of stationary states and dynamical quantum phase transitions. We investigate the precursors of these phenomena and their dynamical consequences in finite (closed and open) bound systems - e.g., systems of interacting qubits or systems of qubits coupled to quantum field modes. We are interested, e.g., in the influence of critical phenomena on the efficiency of the preparation of correlated quantum states or their role in various atypical dynamical effects. We also study the formation of critical structures in quantum tunneling and scattering. The second key area of our research is focused on time correlations and other complex dynamical properties of quantum chaotic systems.

Links

• ipnp.cz
• ipnp.cz/cejnar/publikace/clanky
• pavelstransky.cz/
• github.com/PavelStransky
• ipnp.cz/strelecek

Publications

Driving of an open quantum system at finite temperature across first- and second-order quantum phase transitions
F. Matus, P. Cejnar, Phys. Rev. E 111, 044104 (2025)

Quantum geometry in many-body systems with precursors of criticality
J. Střeleček, P. Cejnar, Phys. Rev. A 111, 012211 (2025)

Unitary collapse of Schrödinger's cat state
P. Stránský , P. Cejnar, R. Filip, Phys. Rev. A 110, L030202 (2024)

Decoherence-assisted quantum driving
P. Cejnar, P. Stránský, J. Střeleček, F. Matus, Phys. Rev. A 107, L030603 (2023)

Search for optimal driving in finite quantum systems with precursors of criticality
F. Matus, J. Střeleček, P. Stránský, P. Cejnar, Phys. Rev. A 107, 012216 (2023)

Stabilization of product states and excited-state quantum phase transitions in a coupled qubit-field system
P. Stránský, P. Cejnar, R. Filip, Phys. Rev. A 104, 053722 (2021)

Excited-state quantum phase transitions
P. Cejnar, P. Stránský, M. Macek, M. Kloc, J. Phys. A: Math. Theo. 54, 133001 (2021)

Complex density of continuum states in resonant quantum tunneling
P. Stránský, M. Sindelka, M. Kloc, P. Cejnar, Phys. Rev. Lett. 125, 020401 (2020)

Collective performance of a finite-time quantum Otto cycle
M. Kloc, P. Cejnar, G. Schaller, Phys. Rev. E 100, 042126 (2019)

Grants

Critical effects in quantum dynamics, Czech Science Foundation 2025-27

Dynamical signatures of excited-state quantum phase transitions, Czech Science Foundation 2020-23