An acoustic probe for quantum vorticity in Bose-Einstein condensates

TL;DR

This paper demonstrates that wavefront deformation of sound in rotating Bose-Einstein condensates reveals the hydrodynamic Aharonov-Bohm effect, providing a new method to probe quantum vorticity and turbulence.

Contribution

It introduces the use of acoustic wavefront deformation as a probe for quantum vorticity in Bose-Einstein condensates, extending the understanding of the Aharonov-Bohm effect in quantum fluids.

Findings

Wavefront deformation shows a phase shift proportional to vortex winding number.

Phase shift is observable in both phase and density fluctuations.

Lattice vortices produce a total phase shift proportional to the number of vortices.

Abstract

We investigate the deformation of wavefronts of sound waves in rotating Bose-Einstein condensates. In irrational fluid flows Berry et al. identified this kind of deformation as the hydrodynamic analogue of the Aharonov-Bohm effect. We study this effect in Bose-Einstein condensates and obtain the Aharonov-Bohm phase shift at all wavelengths. We show that this deformation of wave fronts is seen in both phase and density fluctuations. For wavelengths larger than the healing length, the phase fluctuations experience a phase shift of the order of $2\pi$ times the winding number. We also consider lattices of vortices. If the angular momentum of the vortices are aligned, the total phase shift is $2\pi$ times the number of vortices in the condensate. Because of this behaviour the hydrodynamic Aharonov-Bohm can be utilized as a probe for quantum vorticity, whose experimental realization could offers an alternative route to investigate quantum turbulence in the laboratory.