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Q: Fachverband Quantenoptik und Photonik
Q 28: Poster – Quantum Optics
Q 28.5: Poster
Dienstag, 3. März 2026, 17:00–19:00, Philo 2. OG
Depletion dynamics of a Bose-Einstein condensate in a dissipative optical cavity — •Gage Harmon1, Giovanna Morigi1, Tom Schmit1, and Simon Jäger2 — 1Saarland University — 2University of Bonn
We study the depletion dynamics of a driven homogeneous Bose*Einstein condensate (BEC) strongly interacting with an optical cavity. Working in the bad-cavity regime, we eliminate the photonic degrees of freedom to obtain an effective atom-only master equation. Applying Bogoliubov theory, we derive the dynamics of the covariance matrix of the cavity-coupled atomic fluctuations. The resulting Lyapunov equation captures fluctuations arising from coherent and dissipative cavity-mediated interactions, as well as diffusive cavity shot noise. This system exhibits a self-organization (SO) phase transition and we analyze the depletion of the BEC in the normal (below threshold) and self-organized (above threshold) phases. Below threshold, we define an effective temperature for the cavity-coupled Bogoliubov mode and, in the weak-driving limit, derive an analytic expression consistent with previous results. Above threshold, the dominant depletion mechanism crosses over: near the SO transition, diffusion dominates, whereas deeper in the SO phase cavity-mediated atomic fluctuations prevail. We compare these cavity-induced depletion rates with those from short-range contact interactions obtained from Bogoliubov theory. With this we identify regimes in which cavity dissipation can, in principle, stabilize the condensate.
Keywords: Quantum depletion; Cavity-mediated interactions; Bogoliubov theory; Bose-Einstein condensate