Light-induced localized vortices in multicomponent Bose-Einstein condensates

We study continuous interaction of a trapped two-component Bose-Einstein condensate with light fields in a Λ-type configuration. Using light beams with orbital angular momentum, we theoretically show how to create a stable, pinned vortex configuration, where the rotating component is confined to the region surrounded by the second, nonrotating component. The atoms constituting this vortex can be localized in volumes much smaller than the volume occupied by the second component. We also show that the vortex position can be changed dynamically by moving the laser beams, provided the beams' movement speed remains below the speed of sound. This allows us to use the localized vortex to stir the second component, and to determine the superfluid flow's critical velocity.