Dynamics of Vortices in Bose-Einstein Condensates with Internal Degrees of Freedom

具有内部自由度的玻色-爱因斯坦凝聚体中的涡动力学

基本信息

批准号：
16540359
负责人：
KUWAMOTO Takeshi
金额：
$ 2.24万
依托单位：
Gakushuin university
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

We have studied the dynamics of the multi-charged single quantum vortex in gaseous Bose-Einstein condensates. The vortices were created by topological way which was realized by controlling the atomic spin in the condensates confined in a magnetic trap. First, we created the condensates of atomic ^<87>Rb in the magnetic trap by well known evaporative cooling procedure. Second, we reversed the atomic spins in the condensate by changing the magnetic bias field from 0.5G to -0.5G. We searched the most efficient time for vortex generation by changing the field-reverse time from 1ms to 10ms. The vortices were created in 100-% efficiency when the reverse time was 5ms. Because of the atomic spin of two, the charge of vortices is four in our case.The vortices were disappeared for about 10ms, because the condensates were elongated due to a deformation of magnetic trap potential resulting in the field reversal. In order to avoid this, we tried to transfer the condensates with vortex in the optical trap. Since the potential shape does not change by the magnetic fields for this trap, condensates would be stably confined in the trap, and the lifetime of vortex would be expected to lengthen.We successfully transferred the condensates with vortex from the magnetic trap to optical trap. As a result, the enlargement of the condensates was suppressed, and the measured lifetime of vortices was about 20ms. We sometimes measured two vortices in a condensate at the trap time of about 20ms. We expect that these vortices are due to decay of a four-charge single vortex. As a future work, we would like to demonstrate this dynamics in detail.

我们已经研究了气态玻色子冷凝水中多电荷单量子涡流的动力学。涡旋是通过拓扑方式创建的，该方式是通过控制磁陷阱中的冷凝物中的原子自旋而实现的。首先，我们通过众所周知的蒸发冷却程序在磁陷阱中创建了原子 ^<87> rb的冷凝物。其次，我们通过将磁性偏置场从0.5g更改为-0.5g，逆转了冷凝物中的原子自旋。我们通过将场不转换时间从1MS更改为10ms来搜索涡旋生成的最有效时间。当反向时间为5ms时，涡旋的效率为100％。由于两种原子自旋，在我们的情况下，涡旋的电荷为四个。涡旋消失了约10ms，因为由于磁性陷阱电位的变形导致磁场逆转，因此冷凝物被拉长。为了避免这种情况，我们试图在光学陷阱中以涡流传递冷凝物。由于潜在的形状不会因该陷阱的磁场而变化，因此冷凝水将稳定限制在陷阱中，并且预期涡流的寿命将延长。我们成功地将涡流从磁陷阱转移到光学陷阱。结果，抑制冷凝物的扩大，涡旋的测量寿命约为20ms。有时，我们在约20ms的陷阱时间中在冷凝物中测量了两个涡流。我们预计这些涡旋是由于四个充电的单个涡流的衰减所致。作为未来的工作，我们想详细说明这种动态。