Freiburg 2024 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 3: Bosonic Quantum Gases I (joint session Q/A)
A 3.4: Vortrag
Montag, 11. März 2024, 11:45–12:00, Aula
Out-of-equilibrium dynamics and phases of an atomic BEC coupled to an optical cavity — •Gage Harmon1, Giovanna Morigi1, and Simon Jäger2 — 1Saarland University — 2University of Kaiserslautern-Landau
We study the pattern formation of a laser-driven atomic Bose-Einstein condensate coupled to a single lossy mode of an optical cavity. In our work, we focus on the regime where the effective cavity detuning depends strongly on the dispersive AC Stark shift, and where the cavity relaxation rate is fast compared to the typical atomic relaxation rate. This results in a feedback between the atomic pattern and cavity field that allows for a parameter regime where the cavity field is unable to stabilize the atomic configuration. Instead, the system enters a dynamical phase where the atomic pattern and cavity field exhibit oscillations. We analyze this behavior using a mean-field approach that describes the coupled dynamics of the atoms and cavity field. In addition, working in the bad-cavity regime allows us to derive equations of motion where the cavity degrees of freedom are eliminated, massively improving the integration time. We benchmark and validate these equations of motion and showcase that the existence of limit cycle phases does not require a treatment of the cavity field and atoms to be on equal timescales. Remarkably, we demonstrate that the presence of non-conservative forces which require both, dissipation and a prominent AC Stark shift, are the key mechanisms that results in limit cycle and chaotic phases.
Keywords: Driven-dissipative; Bose-Einstein condensate; Limit cycle; Self-organization