Collapse of spin-orbit-coupled Bose-Einstein condensates
Collapse of spin-orbit-coupled Bose-Einstein condensates
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自旋轨道耦合玻色-爱因斯坦凝聚态的塌缩
DOI：
10.1103/physreva.91.043604
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发表时间：
2015-04-06
影响因子：
2.9
通讯作者：
Chen, Xi
中科院分区：
文献类型：
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作者：
Mardonov, Sh.;Sherman, E. Ya.;Chen, Xi
如果原子之间的吸引力足够强，有限大小的准二维玻色-爱因斯坦凝聚体就会坍塌。本文提出了具有原子间引力和自旋轨道耦合的凝聚体坍缩理论。我们考虑了自旋轨道耦合的两种实现：轴向Rashba耦合和平衡的、有效的一维Rashba- dresselhaus耦合。在这两种情况下，与自旋轨道耦合强度成正比的自旋相关的“异常”速度起着至关重要的作用。对于Rashba耦合，该速度在密度流中形成离心分量，与粒子间吸引力产生的离心分量相反，并防止在足够强的耦合下坍塌。对于平衡的Rashba-Dresselhaus耦合，自旋相关的速度可以在一维空间上分裂初始态并形成自旋投影波包，从而降低总凝聚密度。根据自旋轨道耦合强度、原子间吸引力和初始状态的不同，这种分裂要么阻止坍缩，要么改变坍缩过程。这些结果表明，坍缩可以通过自旋-轨道耦合来控制，从而扩展了吸引原子凝聚物的存在范围。
A finite-size quasi two-dimensional Bose-Einstein condensate collapses if the attraction between atoms is sufficiently strong. Here we present a theory of collapse for condensates with the interatomic attraction and spin-orbit coupling. We consider two realizations of spin-orbit coupling: the axial Rashba coupling and balanced, effectively one-dimensional, Rashba-Dresselhaus one. In both cases spin-dependent "anomalous" velocity, proportional to the spin-orbit coupling strength, plays a crucial role. For the Rashba coupling, this velocity forms a centrifugal component in the density flux opposite to that arising due to the attraction between particles and prevents the collapse at a sufficiently strong coupling. For the balanced Rashba-Dresselhaus coupling, the spin-dependent velocity can spatially split the initial state in one dimension and form spin-projected wavepackets, reducing the total condensate density. Depending on the spin-orbit coupling strength, interatomic attraction, and the initial state, this splitting either prevents the collapse or modifies the collapse process. These results show that the collapse can be controlled by a spin-orbit coupling, thus, extending the domain of existence of condensates of attracting atoms.