玻色-爱因斯坦凝聚体中非线性相互作用对量子共振棘流的影响  

Effects of nonlinearity on quantum resonance ratchet

作　　者：赵文垒[1,2,3] 豆福全[1] 王建忠[1] 

机构地区：[1]北京理工大学物理学院,北京100081 [2]北京应用物理与计算数学研究所,计算物理国家重点实验室,北京100088 [3]北京大学应用物理与技术研究中心,高能量密度物理数值模拟教育部重点实验室,北京100084

出　　处：《物理学报》2012年第22期100-105,共6页Acta Physica Sinica

基　　金：国家高技术研究发展计划(863计划)(批准号:2011AA120101);国家重点基础研究发展计划(973计划)(批准号:2011CB921503)资助的课题~~

摘　　要：研究了玻色-爱因斯坦凝聚体中非线性相互作用对量子共振棘流的影响.满足量子共振条件的周期驱动使得波包在动量空间出现弹道扩散,当波包扩散具有特定方向时,系统就出现定向的动量流.弱非线性相互作用下的冷原子分成两簇,它们分别受到方向相反的稳定周期驱动力,以各自恒定的加速度沿相反方向运动.波包在动量空间的扩散表现为两个稳定的沿相反方向运动的峰.非线性相互作用的增强使得正方向运动的冷原子减少,负方向运动的冷原子增加,从而系统的动量流减弱甚至反转.当非线性相互作用足够强时,动量空间中的波包只有一个稳定的峰,且峰值对应的动量不随时间变化.此时冷原子受的周期驱动力为零,定向的动量流消失.We investigate the effect of the nonlinear interaction on the quantum resonance ratchet for the periodically kicked Bose-Einstein condensate that is realized on a ring. In the noninteracting case, the wave packet spreads asymmetrically in momentum space, leading to a directed current. We show that for the weak nonlinear interaction, the probability density distribution in momentum space has two peaks which linearly shift to ward positive and negative momentum, respectively. The force periodically acting on each peak is a constant with time evolution. The competition between the motions of the two parts of cold atoms leads to the reduce or the revival of the momentum current. For the strong nonlinearity, the momentum distribution has only one peak which does not shift with time. The force on this peak is almost zero with time evolution, thus the directed current varnishes.

关 键 词：玻色-爱因斯坦凝聚 量子共振 棘流 

分 类 号：O431.2[机械工程—光学工程]