Dicke-Type Phase Transition in Bose—Einstein Condensate

Chris Hamner, Chunlei Qu, Yongping Zhang +4 more

Ni Liu, Xiuqin Zhao, J.-Q. Liang

Simsarian, Denschlag, Clark +6 more

Yixiao Huang, Zheng-Da Hu

Recently, strong spin-orbit coupling with equal Rashba and Dresselhaus strength has been realized in neutral atomic Bose-Einstein condensates via a pair of Raman lasers. In this report, we investigate spin and field squeezing of the ground state in spin-orbit coupled Bose-Einstein condensate. By mapping the spin-orbit coupled BEC to the well-known quantum Dicke model, the Dicke type quantum phase transition is presented with the order parameters quantified by the spin polarization and occupation number of harmonic trap mode. This Dicke type quantum phase transition may be captured by the spin and field squeezing arising from the spin-orbit coupling. We further consider the effect of a finite detuning on the ground state and show the spin polarization and the quasi-momentum exhibit a step jump at zero detuning. Meanwhile, we also find that the presence of the detuning enhances the occupation number of harmonic trap mode, while it suppresses the spin and the field squeezing.

Wangjun Lu, Zhen Li, Le‐Man Kuang

We investigate nonlinear Dicke quantum phase transition (QPT) induced by inter-atomic nonlinear interaction and its quantum witness in a cavity-Bose–Einstein-condensate (BEC) system. It is shown that inter-atomic nonlinear interaction in a cavity BEC system can induce first-order Dicke QPT. It is found that this nonlinear Dicke QPT can happen in an arbitrary coupling regime of the cavity and atoms. It is demonstrated that the quantum speed limit time can witness the Dicke QPT through its sudden change at the critical point of the QPT.

R. Lacaze, Pierre Lallemand, Yves Pomeau A +1 more