We examine the conditions that give rise to metastable, persistent currents in a trapped Bose-Einstein condensate. A necessary condition for the stability of persistent currents is that the trapping potential is not a monotonically increasing function of the distance from the trap center. Persistent currents also require that the interatomic interactions are sufficiently strong and repulsive. Finally, any off-center vortex state is shown to be unstable, while a driven gas shows hysteresis.
Kärkkäinen, K., Christensson, J., Reinisch, G., Kavoulakis, G.M. and Reimann, S.M., "Metastability of persistent currents in trapped gases of atoms", Physical Review A, 76, p. 43627 (2007) (doi:10.1103/PhysRevA.76.043627)