Kármán vortex street in spin-1 Bose–Einstein condensate

The dynamics of spin-1 Bose–Einstein condensate with a antiferromagnetic spin interaction through a moving obstacle potential are studied numerically. Various combinations of coreless vortex patterns are observed in two components. The average ratio of the distance between two vortex rows to the distance between two vortex pairs in a row is about 0.2, which is less than the stability criterion 0.28 for classical fluids. The angular velocity of the vortex street and the distance between two point vortices in a pair oscillate approximately periodically around an average value. The density of vortex-like structure also produces drag force, but it is very weak and the direction is opposite to the drag force generated by the quantum vortex. Finally, we provide an experimental protocol for the above realization and observation.