Lowest Landau Level vortex structure of a Bose-Einstein condensate rotating in a harmonic plus quartic trap

TL;DR

This paper studies vortex patterns in a rotating Bose-Einstein condensate within a harmonic plus quartic trap, revealing complex vortex structures including distorted Abrikosov lattices and central multiply quantized vortices.

Contribution

It demonstrates that in the small anharmonicity limit, the Gross-Pitaevskii energy can be minimized using Lowest Landau Level wave functions, providing new theoretical insights.

Findings

Vortex pattern is infinite but non-uniform.

Numerical simulations show distorted Abrikosov lattice.

Multiply quantized vortices appear at the trap center.

Abstract

We investigate the vortex patterns appearing in a two-dimensional annular Bose-Einstein condensate rotating in a quadratic plus quartic confining potential. We show that in the limit of small anharmonicity the Gross-Pitaevskii energy can be minimized amongst the Lowest Landau Level wave functions and use this particular form to get theoretical results in the spirit of [A. Aftalion X. Blanc F. Nier, Phys. Rev. A 73, 011601(R) (2006)]. In particular, we show that the vortex pattern is infinite but not uniform. We also compute numerically the complete vortex structure: it is an Abrikosov lattice strongly distorted near the edges of the condensate with multiply quantized vortices appearing at the center of the trap.