对称双势阱玻色-爱因斯坦凝聚系统在周期驱动下的动力学相变及其量子纠缠熵表示

研究了在对称双势阱玻色-爱因斯坦凝聚体系粒子间相互作用项上外加周期调制而引起的系统动力学相变，特别地研究了该系统通向混沌的相变过程.发现在一定驱动参数下，当外加调制频率与系统固有频率达到共振时，相平面会出现不稳定性现象，即混沌.在混沌区域，粒子在各量子态随机分布，平均布居数差在零附近波动.特别地，研究表明，混沌现象的出现可以用量子纠缠熵来表征，混沌现象出现时，两种平均纠缠熵都趋于它们的最大值. 关键词： 玻色-爱因斯坦凝聚 双势阱 混沌 纠缠熵

Phase transition and entanglement entropy of Bose-Einstein condensates in double-well trap under periodic modulation

Dynamical phase transition of Bose-Einstein condensates (BEC) in double-well trap with external periodic modulation applied to the interaction term is investigated in this paper. Particularly, phase transition to chaos is studied. It is found that, when resonance between the modulation frequency and the natural frequency of the system happens, the system turns to instability (chaos) at certain values of the parameters. In the chaotic region, distribution of particles is random, and the average of population difference fluctuates around zero. Especially, chaos can be manifested by the entanglement entropy. In the chaotic zone, both of the average entanglement entropies approach to their maxima.