Free expansion of Bose-Einstein condensates with quantized vortices - art.no. 023605

The expansion of Bose-Einstein condensates with quantized vortices is studi ed by solving numerically the time-dependent Gross-Pitaevskii equation at z ero temperature. For a condensate initially trapped in a spherical harmonic potential, we confirm previous results obtained by means of variational me thods showing that, after releasing the trap, the vortex core expands faste r than the radius of the atomic cloud. This could make the detection of vor tices feasible, by observing the depletion of the density along the axis of rotation. We find that this effect is significantly enhanced in the case o f anisotropic disk-shaped traps. The results obtained as a function of the anisotropy of the initial configuration are compared with the analytic solu tion for a noninteracting gas in three dimensions as well as with the scali ng law predicted for an interacting gas in two dimensions.