Elementary excitations of chiral Bose-Einstein condensates
1 SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University - Edinburgh, EH14 4AS, UK
2 Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics and Statistics, Newcastle University Newcastle upon Tyne NE1 7RU, UK
Received: 3 February 2015
Accepted: 5 May 2015
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 are irregular.
PACS: 67.85.De – Dynamic properties of condensates; excitations, and superfluid flow / 03.75.-b – Matter waves / 03.65.Vf – Phases: geometric; dynamic or topological
© EPLA, 2015