Ionut Danaila
Universite Pierre et Marie Curie, Paris
We consider a rotating Bose-Einstein condensate confined in combined harmonic and quartic traps.� We investigate numerically the behavior of the wave function which solves the three-dimensional Gross Pitaevskii equation and analyze in detail the structure of vortices. For a harmonic potential, we study in detail the line of a single quantized vortex, which has a U or S shape. For a quartic-plus-harmonic potential, the vortex lattice evolves into a vortex array with hole. We also investigate the case of a quartic-minus-harmonic potential: we show that the transition to a vortex array with hole takes place for lower angular velocities, and we find a case for which a transition from a giant vortex to a hole with a circle of vortices around is observed.