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arXiv 1502.03542cond-mat.quant-gas
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玻色-爱因斯坦凝聚体中涡旋脱落的临界速度

Critical Velocity for Vortex Shedding in a Bose-Einstein Condensate

Woo Jin Kwon, Geol Moon, Sang Won Seo, Yong-il Shin

摘要:

本文用运动的排斥高斯激光束测量了高扁玻色-爱因斯坦凝聚体中涡旋脱落的临界速度。作为势垒高度$V_0$的函数,临界速度$v_c$显示出在$V_0 \approx μ$处具有最小值的倾斜结构,其中$μ$是冷凝物的化学势。在固定的$V_0\approx 7μ$下,我们观察到$v_c$与声速$c_s$的比率随着$σ/ξ$的减小而单调增加,其中$σ$是波束宽度,$ξ$是凝结体愈合长度。测量的上限为$v_c/c_s$约为0.4,这是在良好的协议与理论预测的二维超流通过一个圆柱。我们解释了我们的结果与高斯障碍的软边界的密度降低效应,超流性的局部朗道判据的基础上。

英文摘要:

We present measurements of the critical velocity for vortex shedding in a highly oblate Bose-Einstein condensate with a moving repulsive Gaussian laser beam. As a function of the barrier height $V_0$, the critical velocity $v_c$ shows a dip structure having a minimum at $V_0 \approx μ$, where $μ$ is the chemical potential of the condensate. At fixed $V_0\approx 7μ$, we observe that the ratio of $v_c$ to the speed of sound $c_s$ monotonically increases for decreasing $σ/ξ$, where $σ$ is the beam width and $ξ$ is the condensate healing length. The measured upper bound for $v_c/c_s$ is about 0.4, which is in good agreement with theoretical predictions for a two-dimensional superflow past a circular cylinder. We explain our results with the density reduction effect of the soft boundary of the Gaussian obstacle, based on the local Landau criterion for superfluidity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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