Hydrodynamic generation of skyrmions in a two-component Bose-Einstein condensate

Abstract

When an obstacle is moved in a superfluid faster than a critical velocity, quantized vortices are generated behind the obstacle. Here we propose a method to create more complicated topological excitations, three-dimensional skyrmions, behind a moving obstacle. We numerically show that, in a two-component Bose-Einstein condensate, component-dependent obstacle potentials can generate skyrmions in the wake, made up of quantized vortex rings in different components that are linked with each other. The lifetime of generated skyrmions can be prolonged by a guiding potential, which enables the formation of a skyrmion train. II. SKYRMION IN A TWO-COMPONENT BOSE-EINSTEIN CONDENSATEWe consider a two-component BEC at zero temperature, described by the macroscopic wave functions ψ 1 (r, t) and ψ 2 (r, t) in the mean-field approximation. The two-component wave functions can generally be writ-