Tatsuhiko Shirai, Takashi Mori, Seiji Miyashita
We survey phenomena of a cavity system in which many atoms coherently interact with a single quantized photon mode driven by the AC external field in a dissipative environment. It has been known that a strongly external field causes the so-called optical bistability which is a non-equilibrium phase transition for the balance of excitation and dissipation. On the other hand, a strong interaction causes the Dicke transition, which is a phase transition with a spontaneous appearance of excitations of atoms and photons in the equilibrium system as a consequence of the cooperative phenomena. We study the phenomena in full range of the strength of the interaction and the external field, and present a phase diagram of the stationary state. For the strong interaction region, in order to realize the ground state, appropriate form of the dissipative mechanism in the master equation is necessary instead of the conventional Lindblad form. We provide such an extended master equation. Moreover, the rotating wave approximation may not become appropriate, and thus we study both Tavis-Cummings model with rotating wave approximation and the Dicke model without it, and compare the phase diagrams with each other.
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http://arxiv.org/abs/1204.5516
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