在玻色-爱因斯坦凝聚态中类Dicke模型的相变

Dicke-Type Phase Transition in Bose—Einstein Condensate

自旋和轨道耦合为中性的超冷原子在玻色-爱因斯坦凝聚态(BEC)中的玻色系统提供了研究的机会.文章研究此类系统的相变和基态性质.首先将它映射到著名的量子光学中的Dicke模型,Dicke模型描述了一个原子系综和单模光场之间的相互作用.Dicke模型的中心问题是预测了超辐射相和一个正常相之间的量子相变.我们研究在自旋和轨道耦合中的类似Dicke模型的量子相变.采用平均场自旋相干态法,特别是考虑原子之间的相互作用,计算出描述系统的相变点和基态性质的物理量如平均光子数,平均基态能量、两种自旋激化等物理量的解析表达式,得到在相变前后物理量变化的趋势图并与实验结果相比较.

Spin-orbit coupling（SOC） in ultra cold neutral atoms provides the opportunity to study such phenomena in bosonic systems, Here we study the ground state properties of such a system using the field coherent state and show that it can be mapped to the well-known Dike model in quantum optics, which describes the interactions between an ensemble of atoms and an optical field. A central prediction of the Dieke model is a quantum phase transition between a su- perradiant phase and a normal phase, used the average field spin coherent state method, especial- ly considering the interaction between the atoms, calculated the analytical expressions of the phase transition point and physical quantities which describe ground-state properties of the system such as the average number of photons, the mean energy of the ground state, two spin intensifi- cation, obtained the changing figures of physical quantities in the phase transition before and after and the compared with experimental results.