Freiburg 2024 – scientific programme

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A: Fachverband Atomphysik

A 33: Poster VI

A 33.3: Poster

Thursday, March 14, 2024, 17:00–19:00, Tent A

Experimental Observation of Time-Dependent Energy-Level Renormalization near Ultrastrong Couplings in Quantum-Rabi Systems — •Frederike Doerr, Florian Hasse, Alessandra Colla, Ulrich Warring, Heinz-Peter Breuer, and Tobias Schaetz — Institute of Physics, University of Freiburg, Hermann-Herder-Straße 3, D-79104 Freiburg, Germany

A novel theory, extending beyond perturbation theory, elucidates the thermodynamic behavior of open quantum systems interacting with thermal baths: predicting a time-dependent frequency shift, Δ ω(t), arising from the interaction with the environmental mode, dependent on the system-environment coupling (g) and temperature (T) [1]. We investigate changes in the electronic energy levels of a trapped ion strongly connected to a single motional degree of freedom. Employing Ramsey interferometry and analyzing the oscillation frequencies of the system’s coherences, we observe a clear and time-dependent effective shift in the ion’s energy levels, consistent with the theoretical predictions. These findings provide direct evidence of dynamic energy level renormalization in strongly coupled quantum systems, emphasizing the role of memory effects in shaping the system’s energy landscape.

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

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