Bénard–von Kármán vortex street in a dipolar Bose–Einstein condensate

Xi, Zhong-Hong; Zhao, Yong; Shi, Yu-Ren

doi:10.1016/j.physa.2021.125866

Cited by 4 publications

(4 citation statements)

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“…首先将偶极 BEC 囚禁在谐振子势 ext V 中, 然后引入一高斯势 OP V 在 BEC 中作圆周运动，则描述系统的 GP 方程可以表示为 [21][22][23][24][25] 2 2 2 ( , ) ( ) ( , ) 2…”

Section: 理论模型unclassified

“…, 并用虚时演化法计算系统的基态. 然后以所得到的基态作为初始状态, 采用时间劈裂谱方法 [23,[29][30][31] 数 [32,33] )的谐振子外势将 3 2.0 0.5 10 [23] . 通过 Feshbach 共振调节…”

Section: 理论模型unclassified

“…Kwon 小组进行了大量实验研究 [15][16][17] , 2016 年发现排斥高斯激光束在高度扁圆的 BEC 中运动时, 具有相同旋转方向的涡旋对周期性的从激光束脱落并在尾流中整齐排列形成类似 BvK 涡街的结构 [18] . 偶极相互作用作为一种各项异性的长程相互作用不仅为原子气体 BEC 提供了更多的控制参量, 而且使得 BEC 系统在理论和实验上表现出更加新奇的物理现象 [19][20][21][22][23] , 也为偶极 BEC 在量子计算等领域的应用提供了更多的可能性 [24] . 就目前相关报道来看, 关于 BEC 中 BvK 涡街的理论和实验研究大多考虑障碍物沿某一方向直线运动的情形.…”

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von Kármán vortex street in dipole BEC induced by a circular moving potential

Xi¹,

Zhao²,

Guang-bi³

et al. 2023

Acta Phys. Sin.

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The dynamical behaviors of a dipole Bose-Einstein condensates (BEC), which is stirred by a circular moving Gaussian potential, are numerically investigated using the mean-field theory. In this paper, we assume that the atoms is polarized along the z-axis. Firstly, the stationary state of the system is obtained by solving the quasi-two-dimensional Gross-Pitaevskki equation numerically under periodic boundary conditions. And then, taking the obtained ground state as the initial condition, the dynamic evolution of the dipole BEC system is studied by the time-splitting Fourier spectrum method. Four types of emission, namely, the stable laminar flow, vortex dipoles, Bénard-von Kármán (BvK) vortex street and irregular turbulence, are observed in the wake when the velocity and size of the Gaussian potential change gradually. When the velocity of the Gaussian potential reaches the critical velocity of vortex excitation, vortex pairs with opposite circulation alternately fall off from the surface of the Gaussian potential. Due to the interaction between the vortex dipoles, the dipoles rotate by their own center. Finally, a ring structure will be formed and exist in the wake stably for a long time. With the increase of the velocity of Gaussian potential, the period of dipoles shedding is also shortened. For the appropriate velocity and size of the Gaussian potential, the vortex pairs with same circulations will periodically fall off from the Gaussian potential and stably distributed on the inner and outer rings, forming BvK vortex street. Our caculation reveals that the conditions for forming BvK vortex street when the dipole BEC is stirred with a circular moving potential are very restricted. When the velocity or size of the Gaussian potential continues to increase, the phenomenon of the periodic vortex pairs shedding in the wake of the Gaussian potential will disappear, and the shedding pattern of the dipole BEC becomes irregular. The parameter regiemes of different dipole interactions was obtained by systematic numerical calculation using experimental parameters. The influences of dipole interactions, velocity and size of the Gaussian potential on different emission are discussed. In the end, the physical mechanism of different emission is analyzed by calculating the drag force acting on Gaussian potential.

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von Kármán vortex street in dipole BEC induced by a circular moving potential

Xi¹,

Zhao²,

Guang-bi³

et al. 2023

Acta Phys. Sin.

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“…The nucleation of vortices is a process that takes place in different quantum flows, like BECs [14,15], superfluid of light [16,17], and superfluid 4 He [18]. Numerical simulations in models of BECs and dipolar BECs showed that the obstacle can create regular or irregular vortex patterns at its wake, in particular the creation of a Bénard-von Kármán vortex street [19][20][21][22].…”

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confidence: 99%