No Effect of Steady Rotation on Solid $^4$He in a Torsional Oscillator

TL;DR

This study tested whether steady rotation affects solid helium-4 in a torsional oscillator and found no observable effects, challenging previous claims of quantum phenomena induced by rotation.

Contribution

The paper provides the first high-sensitivity measurement showing no effect of steady rotation on solid helium-4, contradicting earlier reports of quantum effects under rotation.

Findings

No step-like features in resonant frequency or dissipation during rotation

No history dependence observed in the measurements

Changes during rotation consistent with an empty cell

Abstract

We have measured the response of a torsional oscillator containing polycrystalline hcp solid $^{4}$He to applied steady rotation in an attempt to verify the observations of several other groups that were initially interpreted as evidence for macroscopic quantum effects. The geometry of the cell was that of a simple annulus, with a fill line of relatively narrow diameter in the centre of the torsion rod. Varying the angular velocity of rotation up to 2\,rad\,s$^{-1}$ showed that there were no step-like features in the resonant frequency or dissipation of the oscillator and no history dependence, even though we achieved the sensitivity required to detect the various effects seen in earlier experiments on other rotating cryostats. All small changes during rotation were consistent with those occurring with an empty cell. We thus observed no effects on the samples of solid $^4$He attributable to steady rotation.