论文标题
在玻色网冷凝物中高斯障碍物的最低临界速度
Minimum critical velocity of a Gaussian obstacle in a Bose-Einstein condensate
论文作者
论文摘要
当超氟流过障碍物时，可以在某个临界速度上方的尾流中创建量化的涡旋。在Kwon等人的实验中。 [物理。 Rev. A 91，053615（2015）]，使用移动的排斥高斯潜能和$ V_C $最小化$ V_0 $ V_0 $ V_0 $ $ V_0 $ $ V_0 $ $ V_0 $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $。在这里，我们在数字上研究了二维涡流脱落的$ v_0 $的临界涡流脱落的演变，并表明，关键强度的最低$ v_c $ $ v_ {0c} \ y $ $ $ $ $ y $ y $ y $ y $ $ y $ $ y $ $ $ y $ y $ y $ y $ y $ y $ $ $ $ $ $ $ $ y $ $ $ $ $ $ $ y $ $ $ $ $ $ $ $ $ $ $ y $ y $ $ $ $ $ $ $ $ $ $ $ $ $ $来自局部密度降低和反击障碍物的涡旋销钉效应。检查了在$ v_c $以下的移动障碍物周围的超级流的空间分布。障碍物尖端的粒子密度随着$ v_0 $的增加到$ v_ {c0} $的增加而降低，并且在临界强度下，涡旋偶极子突然被移动的障碍物形成并拖动，表明涡旋固定的发作。最低$ v_c $以障碍物尺寸$σ$显示为$ v_c \simσ^{ - γ} $，带有$γ\约1/2 $。
When a superfluid flows past an obstacle, quantized vortices can be created in the wake above a certain critical velocity. In the experiment by Kwon et al. [Phys. Rev. A 91, 053615 (2015)], the critical velocity $v_c$ was measured for atomic Bose-Einstein condensates (BECs) using a moving repulsive Gaussian potential and $v_c$ was minimized when the potential height $V_0$ of the obstacle was close to the condensate chemical potential $μ$. Here we numerically investigate the evolution of the critical vortex shedding in a two-dimensional BEC with increasing $V_0$ and show that the minimum $v_c$ at the critical strength $V_{0c}\approx μ$ results from the local density reduction and vortex pinning effect of the repulsive obstacle. The spatial distribution of the superflow around the moving obstacle just below $v_c$ is examined. The particle density at the tip of the obstacle decreases as $V_0$ increases to $V_{c0}$ and at the critical strength, a vortex dipole is suddenly formed and dragged by the moving obstacle, indicating the onset of vortex pinning. The minimum $v_c$ exhibits power-law scaling with the obstacle size $σ$ as $v_c\sim σ^{-γ}$ with $γ\approx 1/2$.
