Threshold for creating excitations in a stirred superfluid ring
Threshold for creating excitations in a stirred superfluid ring
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在搅拌的超流环中产生激发的阈值
DOI：
10.1103/physreva.88.063633
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发表时间：
2013
影响因子：
2.9
通讯作者：
G. Campbell
中科院分区：
文献类型：
--
作者：
K. Wright;R. B. Blakestad;C. Lobb;W. Phillips;G. Campbell
我们已经测量了当环形玻色-爱因斯坦凝聚体被一个高度可变的旋转（光学）势垒搅动时，产生长寿命激发的阈值。当势垒高度为化学势的一半或以上时，我们观察到循环状态变化的临界势垒速度远小于声音在环中传播的速度。在这个制度中，我们主要观察到离散跳跃（相位滑移）从非循环的初始状态到一个简单的，定义明确的，持续的当前状态。对于较低的势垒高度，临界势垒速度，我们观察到的循环状态的变化是较高的，并接近有效声速为零的势垒高度。在这个小障碍制度的冷凝水的响应是更复杂的，涡核出现在大部分的冷凝水。我们发现，激发阈值随势垒高度的变化与一个有效的一维流体动力学模型的预测定性一致。
We have measured the threshold for creating long-lived excitations when a toroidal Bose-Einstein condensate is stirred by a rotating (optical) barrier of variable height. When the barrier height is on the order of or greater than half of the chemical potential, the critical barrier velocity at which we observe a change in the circulation state is much less than the speed for sound to propagate around the ring. In this regime we primarily observe discrete jumps (phase slips) from the non-circulating initial state to a simple, well-defined, persistent current state. For lower barrier heights, the critical barrier velocity at which we observe a change in the circulation state is higher, and approaches the effective sound speed for vanishing barrier height. The response of the condensate in this small-barrier regime is more complex, with vortex cores appearing in the bulk of the condensate. We find that the variation of the excitation threshold with barrier height is in qualitative agreement with the predictions of an effective 1D hydrodynamic model.