Superfluid vortex front at T -> 0: Decoupling from the reference frame

TL;DR

This paper reports the first experimental evidence that superfluid 3He-B decouples from the container at near-zero temperatures, with vortex dynamics showing a reduced superfluid rotation compared to the container.

Contribution

It provides the first measurements of thermal dissipation signals during vortex front motion at very low temperatures, confirming superfluid decoupling from the reference frame.

Findings

Vortex density falls below equilibrium at low temperatures

Superfluid rotation is less than container rotation at T -> 0

First direct evidence of superfluid decoupling in this regime

Abstract

Steady-state turbulent motion is created in superfluid 3He-B at low temperatures in the form of a turbulent vortex front, which moves axially along a rotating cylindrical container of 3He-B and replaces vortex-free flow with vortex lines at constant density. We present the first measurements on the thermal signal from dissipation as a function of time, recorded at 0.2 Tc during the front motion, which is monitored using NMR techniques. Both the measurements and the numerical calculations of the vortex dynamics show that at low temperatures the density of the propagating vortices falls well below the equilibrium value, i.e. the superfluid rotates at a smaller angular velocity than the container. This is the first evidence for the decoupling of the superfluid from the container reference frame in the zero-temperature limit.