Vortex pair excitation in a Bose-Einstein condensate by moving potential barriers

The subsonic motion regime of a potential barrier in a Bose-Einstein condensate is considered. It is characterized by a critical velocity above which vortex pairs appear with opposite topological charges (“vortex-antivortex” pairs). The theoretical picture developed is confirmed by the results of numerical simulations within the framework of the Gross-Pitaevskii equation.