Elementary excitations of chiral Bose-Einstein condensates

TL;DR

This paper investigates the collective excitations of chiral Bose-Einstein condensates influenced by density-dependent gauge potentials, revealing unique superfluid behaviors and mode couplings due to broken Galilean invariance.

Contribution

It introduces an interacting gauge theory for BECs with density-dependent gauge potentials, highlighting novel superfluid states and mode dynamics.

Findings

Dipole mode frequency depends on mass current strength

Coupling between center of mass and shape oscillations

Irregular dynamics in nonlinear regime

Abstract

We study the collective modes of a Bose-Einstein condensate subject to an optically induced density-dependent gauge potential. The corresponding interacting gauge theory lacks Galilean invariance, yielding an exotic superfluid state. The nonlinear dynamics in the presence of a current nonlinearity and an external harmonic trap are found to give rise to dynamics which violate Kohn's theorem; where the frequency of the dipole mode strongly depends on the strength of the mass current in the gas. The linearised spectrum reveals how the centre of mass and shape oscillations are coupled, whereas in the strongly nonlinear regime the dynamics is irregular.