Abstract
The dynamics of pseudo-spin-1/2 Bose-Einstein condensates with weak spin-orbit coupling through a moving obstacle potential are studied numerically. Four types of wakes are observed and the phase diagrams are determined for different spin-orbit coupling strengths. The conditions to form Bénard–von Kármán vortex street are rather rigorous, and we investigate in detail the dynamical characteristics of the vortex streets. The two point vortices in a pair rotate around their center, and the angular velocity and their distance oscillate periodically. The oscillation intensifies with increasing spin-orbit coupling strengths, and it makes part of the vortex pairs dissociate into separate vortices or combine into single ones and destroys the vortex street in the end. The width of the street and the distance between two consecutive vortex pairs of the same circulation are determined by the potential radius and its moving velocity, respectively. The ratios are independent of the spin-orbit coupling strength and fall in the range , which is a little smaller than the stability criterion 0.28 for classical fluids. Proper ratios are necessary to form Bénard–von Kármán vortex street, but the spin-orbit coupling strength affects the stability of the street patterns. Finally, we propose a protocol to experimentally realize the vortex street in spin-orbit-coupling Bose-Einstein condensates.
- Received 11 November 2019
- Accepted 2 September 2020
- Corrected 22 September 2020
DOI:https://doi.org/10.1103/PhysRevE.102.032217
©2020 American Physical Society
Physics Subject Headings (PhySH)
Corrections
22 September 2020
Correction: An NSF grant number was missing in the Acknowledgments and has been inserted.