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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.

研究了玻色-爱因斯坦凝聚体中多电荷单量子涡旋的动力学性质。通过控制磁阱中凝聚体中原子的自旋，以拓扑方式产生涡旋。首先，我们<87>利用蒸发冷却的方法在磁阱中产生了铷原子的凝聚态。第二，我们通过改变偏磁场从0.5G到-0.5G来反转凝聚体中的原子自旋。我们通过改变场反转时间从1 ms到10 ms来寻找产生涡旋的最有效时间。当反向时间为5 ms时，以100%的效率产生涡流。由于原子的自旋为2，在我们的例子中，涡旋的电荷为4，涡旋消失了大约10 ms，这是由于磁阱势的变形导致场反转而导致凝聚体被拉长。为了避免这种现象的发生，我们尝试在光阱中引入涡旋来转移凝聚态。由于势阱的形状不随磁场的变化而改变，因此，凝聚态将被稳定地限制在阱中，并且涡旋的寿命有望延长，我们成功地将带有涡旋的凝聚态从磁阱转移到光阱中。结果表明，凝结体的膨胀得到了抑制，测得的涡旋寿命约为20 ms。我们有时在一个凝聚体中测量到两个涡旋，捕获时间约为20 ms。我们预计，这些旋涡是由于一个四电荷单涡衰变。作为未来的工作，我们想详细展示这种动态。