Pressure-driven flow of solid helium

TL;DR

This study investigates the flow of solid helium under pressure using a piezoelectric diaphragm, finding no evidence of supersolid flow at low temperatures, thus challenging previous torsional oscillator results suggesting supersolidity.

Contribution

The paper introduces a novel pressure-driven flow measurement method to test for supersolidity in solid helium, providing stringent experimental constraints on supersolid flow.

Findings

No low-temperature flow detected in solid helium

Flow speed less than 1.2x10^-14 m/s at low temperatures

Supersolid velocity at least 7 orders of magnitude smaller than critical velocities

Abstract

The recent torsional oscillator results of Kim and Chan suggest a supersolid phase transition in solid 4He. We have used a piezoelectrically driven diaphragm to study the flow of solid helium through an array of capillaries. Our measurements showed no indication of low temperature flow, placing stringent restrictions on supersolid flow in response to a pressure difference. The average flow speed at low temperatures was less than 1.2x10-14 m/s, corresponding to a supersolid velocity at least 7 orders of magnitude smaller than the critical velocities inferred from the torsional oscillator measurements.