Huang Yixiao, Hu Zheng-Da
Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Hong Kong, China.
School of Science, Jiangnan University, Wuxi 214122, China.
Sci Rep. 2015 Jan 26;5:8006. doi: 10.1038/srep08006.
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.
最近，通过一对拉曼激光器在中性原子玻色-爱因斯坦凝聚体中实现了具有相等Rashba和Dresselhaus强度的强自旋-轨道耦合。在本报告中，我们研究了自旋-轨道耦合玻色-爱因斯坦凝聚体基态的自旋和场压缩。通过将自旋-轨道耦合的玻色-爱因斯坦凝聚体映射到著名的量子迪克模型，给出了迪克型量子相变，其序参量由自旋极化和谐波陷阱模式的占据数来量化。这种迪克型量子相变可能由自旋-轨道耦合引起的自旋和场压缩所捕获。我们进一步考虑了有限失谐对基态的影响，并表明自旋极化和准动量在零失谐处呈现阶跃跳跃。同时，我们还发现失谐的存在增加了谐波陷阱模式的占据数，而抑制了自旋和场压缩。
