Kelvin-Helmholtz instability in an atomic superfluid

TL;DR

This paper presents an experimentally feasible method to generate and observe Kelvin-Helmholtz instability in a single-component atomic Bose-Einstein condensate, enabling the study of quantum turbulence and effective viscosity measurement.

Contribution

It introduces a novel approach to induce classical-like shear instabilities in a quantum fluid and demonstrates how to measure its effective viscosity using vortex cluster dynamics.

Findings

Successful generation of Kelvin-Helmholtz instability in BEC

Formation of vortex clusters mimicking classical roll-up

Method for measuring quantum fluid viscosity

Abstract

We demonstrate an experimentally feasible method for generating the classical Kelvin-Helmholtz instability in a single component atomic Bose-Einstein condensate. By progressively reducing a potential barrier between two counter-flowing channels we seed a line of quantised vortices, which precede to form progressively larger clusters, mimicking the classical roll-up behaviour of the Kelvin-Helmholtz instability. This cluster formation leads to an effective superfluid shear layer, formed through the collective motion of many quantised vortices. From this we demonstrate a straightforward method to measure the effective viscosity of a turbulent quantum fluid in a system with a moderate number of vortices, within the range of current experimental capabilities.