Freiburg 2024 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 37: Poster III

Q 37.8: Poster

Mittwoch, 13. März 2024, 17:00–19:00, Tent B

Energy level renormalization in strongly coupled open quantum systems — •Alessandra Colla, Florian Hasse, Frederike Doerr, Ulrich Warring, Tobias Schaetz, and Heinz-Peter Breuer — Institute of Physics, University of Freiburg, Hermann- Herder-Straße 3, D-79104 Freiburg, Germany

When a quantum system interacts strongly with a general environment, the interaction energy they share can be of the same magnitude as the expectation value of the bare system Hamiltonian, and can no longer be neglected. Is it then justified to still consider the bare system Hamiltonian as the operator determining the energy levels of the system? If we observe the system while it is coupled to the environment, would we witness signatures of the interaction energy in the system? If so, how? We show that in the case of a simple Jaynes-Cummings model, the energy levels of the two-level system undergo a renormalization due to the strong interaction with the mode, in accordance with our recent proposal for a theory of open system quantum thermodynamics [1]. This energy level shift, which is in general time-dependent, is determined by the coupling strength and by the initial state of the mode (typically its associated temperature). Furthermore, it is experimentally accessible in suitable platforms, and leads to the well known Lamb-shift for zero mode temperature and in the limit of large detuning.

[1] A. Colla and H.-P. Breuer, Phys. Rev. A 105, 052216 (2022).

Keywords: open quantum systems; quantum thermodynamics; ultrastrong coupling regime