Transition to instability in a periodically kicked Bose-Einstein condensate on a ring
Transition to instability in a periodically kicked Bose-Einstein condensate on a ring
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DOI：
10.1103/physreva.73.013601
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发表时间：
2005-08
影响因子：
2.9
通讯作者：
Jie Liu;Chuanwei Zhang;M. Raizen;Q. Niu
中科院分区：
文献类型：
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作者：
Jie Liu;Chuanwei Zhang;M. Raizen;Q. Niu
玻色-爱因斯坦凝聚体的周期性被踢环被认为是量子被踢转子的非线性推广，其中非线性源于凝聚原子之间的平均场相互作用。对于弱相互作用，周期运动反共振变为准周期量子拍频，但仍保持稳定。存在一个临界的相互作用强度，超过这个强度准周期运动变得混乱，导致凝聚体的不稳定性，表现为非凝聚原子数量的指数增长。在稳定的制度，该系统主要保持在两个最低的能量状态，并可以映射到一个自旋模型，从中我们得到的拍频的解析表达式，并讨论了不稳定的路线。我们用数值方法研究了不稳定性发生的参数机制，并揭示了凝聚态和非凝聚态原子的特征密度分布。阿诺德扩散到更高的能量水平被认为是负责过渡到不稳定性。类似的行为被观察到的动态本地化状态基本上是准周期运动，稳定性仍然是弱相互作用，但被破坏的强相互作用。
A periodically kicked ring of a Bose-Einstein condensate is considered as a nonlinear generalization of the quantum kicked rotor, where the nonlinearity stems from the mean-field interactions between the condensed atoms. For weak interactions, periodic motion antiresonance becomes quasiperiodic quantum beating but remains stable. There exists a critical strength of interactions beyond which quasiperiodic motion becomes chaotic, resulting in an instability of the condensate manifested by exponential growth in the number of noncondensed atoms. In the stable regime, the system remains predominantly in the two lowest energy states and may be mapped onto a spin model, from which we obtain an analytic expression for the beat frequency and discuss the route to instability. We numerically explore a parameter regime for the occurrence of instability and reveal the characteristic density profile for both condensed and noncondensed atoms. The Arnold diffusion to higher energy levels is found to be responsible for the transition to instability. Similar behavior is observed for dynamically localized states essentially quasiperiodic motions, where stability remains for weak interactions but is destroyed by strong interactions.