Diffused vorticity approach to the oscillations of a rotating Bose-Einstein condensate confined in a harmonic plus quartic trap

TL;DR

This paper investigates the collective oscillation modes of a rotating Bose-Einstein condensate in a combined harmonic and quartic trap using a diffused vorticity approach and sum rule techniques, revealing vortex oscillation modes.

Contribution

It introduces a diffused vorticity method combined with sum rule calculations to analyze collective modes in a rotating BEC with complex trapping potentials.

Findings

Identification of low-frequency vortex oscillation modes.

Validation of the diffused vorticity approach against numerical solutions.

Discovery of multipole modes associated with vortex dynamics.

Abstract

The collective modes of a rotating Bose-Einstein condensate confined in an attractive quadratic plus quartic trap are investigated. Assuming the presence of a large number of vortices we apply the diffused vorticity approach to the system. We then use the sum rule technique for the calculation of collective frequencies, comparing the results with the numerical solution of the linearized hydrodynamic equations. Numerical solutions also show the existence of low-frequency multipole modes which are interpreted as vortex oscillations.