Flows with fractional quantum circulation in Bose-Einstein condensates induced by nontopological phase defects
Flows with fractional quantum circulation in Bose-Einstein condensates induced by nontopological phase defects
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DOI：
10.1103/physreva.97.013612
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发表时间：
2018-01
影响因子：
2.9
通讯作者：
T. Kanai;W. Guo;M. Tsubota
中科院分区：
文献类型：
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作者：
T. Kanai;W. Guo;M. Tsubota
人们普遍认为，只有在量子化的涡旋存在的情况下，超流体中的旋转运动才能存在。然而，在我们对二维空间中两个轴对称的同心玻色-爱因斯坦凝聚体合并的数值研究中，我们观察到当一个凝聚体具有非零初始角动量时，会出现螺旋暗孤子。这种螺旋暗孤子能够在凝聚体之间传递角动量，并允许合并的凝聚体即使在没有量化涡旋的情况下也能旋转。我们研究了孤子周围的流场，发现它的尖端可以像涡点一样诱导流动，但只有量子化环流的一小部分。由于旋转运动在许多量子输运过程中是必不可少的，这种有趣的非拓扑性“位相缺陷”可能会引起广泛的兴趣。
It is a common view that rotational motion in a superfluid can exist only in the presence of quantized vortices. However, in our numerical studies on the merging of two concentric Bose-Einstein condensates with axial symmetry in two-dimensional space, we observe the emergence of a spiral dark soliton when one condensate has a non-zero initial angular momentum. This spiral dark soliton enables the transfer of angular momentum between the condensates and allows the merged condensate to rotate even in the absence of quantized vortices. We examine the flow field around the soliton and reveal that its sharp endpoint can induce flow like a vortex point but with a fraction of a quantized circulation. This interesting nontopological "phase defect" may generate broad interests since rotational motion is essential in many quantum transport processes.