Dynamics of ring dark solitons in a two-dimensional dipolar Bose-Einstein condensate

We study the dynamics of ring dark solitons in a two-dimensional dipolar Bose-Einstein condensate, which exhibits complicated dynamical behaviors quite different from those in a non-dipolar condensate. We explore the effects of dipolar interaction on the dynamics of ring dark solitons. In the case the polarization direction of dipolar atoms is vertical to the condensate, the dipolar interaction shows isotropy, it is found that there exists a critical value of relative strength between the dipolar and contact interactions for the collapse of shallow ring dark soliton. We also find that the bigger dipolar interaction can induce more vortex-antivortex pairs accompanied by the collapse of ring dark solitons. When the orientation of dipolar atoms is not vertical to the condensate, the dipolar interaction shows anisotropy, the ring dark solitons first shrink to an elliptical configuration and then decay to lump solitons or vortex-antivortex pairs. And we find the vortex recombination, annihilation, oblique collisions, and catching up during the collapse of ring dark solitons.(c) 2022 Published by Elsevier B.V.