Giant vortices in combined harmonic and quartic traps

TL;DR

This paper numerically studies vortex structures in rotating Bose-Einstein condensates within combined harmonic and quartic traps, revealing conditions for giant vortex formation and analyzing their three-dimensional structure.

Contribution

It provides new insights into vortex behavior in combined traps, especially showing giant vortex formation at lower rotation speeds with strong quartic potentials.

Findings

Giant vortices form at higher rotation speeds when harmonic potential dominates.

Strong quartic potentials induce giant vortices at lower rotation speeds.

Detailed analysis of three-dimensional vortex structures.

Abstract

We consider a rotating Bose-Einstein condensate confined in combined harmonic and quartic traps, following recent experiments [V. Bretin, S. Stock, Y. Seurin and J. Dalibard, cond-mat/0307464]. We investigate numerically the behavior of the wave function which solves the three-dimensional Gross Pitaevskii equation. When the harmonic part of the potential is dominant, as the angular velocities $Omega$ increases, the vortex lattice evolves into a giant vortex. We also investigate a case not covered by the experiments or the previous numerical works: for strong quartic potentials, the giant vortex is obtained for lower $Omega$, before the lattice is formed. We analyze in detail the three dimensional structure of vortices.