Zero-energy states in rotating trapped Bose-Einstein condensates

TL;DR

This paper investigates the excitation spectra of rotating 3D Bose-Einstein condensates, revealing a zero-energy Tkachenko mode at certain rotation frequencies, which could be experimentally detectable.

Contribution

It provides the first calculation of low-lying quasiparticle spectra showing a zero-energy Tkachenko mode, challenging previous hydrodynamic predictions.

Findings

Discovery of a minimum in the Tkachenko mode spectrum at intermediate rotation frequencies.

Identification of a zero-energy Tkachenko quasiparticle mode.

Discussion of experimental signatures for detecting the zero mode.

Abstract

We have calculated low-lying quasiparticle excitation spectra of rotating three-dimensional Bose-Einstein condensates. As opposed to the prediction of hydrodynamic continuum theories, we find a minimum in the Tkachenko mode spectrum at intermediate rotation frequencies of the harmonic trap. Such a minimum can harbour a Tkachenko quasiparticle with zero excitation energy. We discuss the experimental signatures of such a zero mode.