arXiv:1202.4125 · Physical Review A

Finite-temperature Dicke phase transition of a Bose-Einstein condensate in an optical cavity

Yuanwei Zhang, Jinling Lian, J.-Q. Liang, Gang Chen, Chuanwei Zhang, Suotang Jia

Published Jan 16, 2013• 13 citations

Abstract

In this paper we investigate the finite-temperature properties of a Bose-Einstein condensate (BEC)-cavity system with a strong nonlinear atom-photon interaction by means of a functional path-integral approach. It is shown that the experimentally observed phase diagram [Baumann, Guerlin, Brennecke, and Esslinger, Nature (London) 464, 1301 (2010)] can be better explained in our finite-temperature theory. More importantly, we identify a new dynamical unstable phase in this experiment. By tuning various experimental parameters, we reveal some rich temperature-driven phase diagrams and, in particular, predict a four-phase coexistence point. Finally, we find analytically that the specific heat in the superradiant phase increases exponentially at lower temperatures. Moreover, it has a large jump at the temperature-driven critical point where the superradiant-normal phase transition occurs. As a result, we argue that the specific heat can serve as a powerful tool to probe the thermodynamic properties of the BEC-cavity system.

DOI: 10.1103/physreva.87.013616

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