Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: Cold Atomic Gases and Superfluids

TT 9.2: Talk

Monday, September 5, 2022, 18:15–18:30, H23

Quantum light-matter fluctuations in driven open cavity BEC systems — •Leon Mixa and Michael Thorwart — I. Institut für Theoretische Physik, Universität Hamburg

When an ultracold atom gas strongly interacts with a pumped cavity light field, effective retarded long-range interactions are induced. They give rise to non-classical states in the light sector, which do not necessarily require non-classical fluctuations in the matter sector. We study theoretically the quantum fluctuations in the light and the matter sectors in different driving regimes. In particular, the photon dissipation channel of the cavity allows for the direct nondestructive measurement of the fluctuations driving the phase transition known in this system. Light-induced density fluctuations drive a superradiant nonequilibrium Dicke quantum phase transition of the atom gas. The photon statistics in the presence of the strongly coupled, pumped atom gas is calculated within a Bogoliubov approach combined with analytic imaginary time path integrals including photon leakage of the cavity. Parameter regimes for squeezed cavity light are identified.