Excitation spectrum of vortex lattices in rotating Bose-Einstein condensates

TL;DR

This paper calculates the excitation spectrum of vortex lattices in rotating Bose-Einstein condensates using a hydrodynamic approach, aligning well with recent experimental measurements and identifying specific mode frequencies.

Contribution

It introduces a hydrodynamic method to accurately predict vortex lattice excitation spectra, including higher-order modes, in rotating Bose-Einstein condensates.

Findings

Good agreement with JILA experimental data

Identification of the $n=2$, $m=0$ mode as a longitudinal mode

Prediction of higher-order compressional modes

Abstract

Using the coarse grain averaged hydrodynamic approach, we calculate the excitation spectrum of vortex lattices sustained in rotating Bose-Einstein condensates. The spectrum gives the frequencies of the common-mode longitudinal waves in the hydrodynamic regime, including those of the higher-order compressional modes. Reasonable agreement with the measurements taken in a recent JILA experiment is found, suggesting that one of the longitudinal modes reported in the experiment is likely to be the $n=2$, $m=0$ mode.