Non-Appearance of Vortices in Fast Mechanical Expansions of Liquid 4He Through the Lambda Transition

TL;DR

This study investigates vortex formation in rapidly cooled liquid helium-4 and finds significantly fewer vortices than predicted by the Kibble-Zurek mechanism, suggesting alternative dynamics during the superfluid transition.

Contribution

The paper presents a novel experimental approach minimizing hydrodynamic vortex creation, revealing a much lower vortex density than theoretical predictions during rapid quenches.

Findings

Vortices are at least 100 times less dense than expected.

Rapid quenches do not produce the anticipated topological defects.

Vortex formation mechanisms may differ from current theories.

Abstract

A new experiment has been performed to study the formation of topological defects (quantized vortices) during rapid quenches of liquid 4He through the superfluid transition, with particular care taken to minimise vortex creation via conventional hydrodynamic flow processes. It is found that the generated vortices, if any, are being produced at densities at least two orders of magnitude less than might be expected on the basis of the Kibble-Zurek mechanism.