Phases of a rotating Bose-Einstein condensate with anharmonic confinement

TL;DR

This paper investigates the phase behavior of a rotating Bose-Einstein condensate in a combined quadratic and quartic potential, identifying three phases and mapping their transitions using variational and numerical methods.

Contribution

It introduces a universal phase diagram for the system and confirms the accuracy of variational results with numerical solutions of the Gross-Pitaevskii equation.

Findings

Identifies three phases: multiple quantization, single quantization, and mixed phase.

Derives a universal phase diagram for the system.

Shows continuous transitions are exact in weak coupling and small anharmonicity limits.

Abstract

We examine an effectively repulsive Bose-Einstein condensate of atoms that rotates in a quadratic-plus-quartic potential. With use of a variational method we identify the three possible phases of the system (multiple quantization, single quantization, and a mixed phase) as a function of the rotational frequency of the gas and of the coupling constant. The derived phase diagram is shown to be universal and the continuous transitions to be exact in the limit of weak coupling and small anharmonicity. The variational results are found to be consistent with numerical solutions of the Gross-Pitaevskii equation.