Discovery of the Acoustic Faraday Effect in Superfluid 3He-B

TL;DR

This paper reports the first observation of the acoustic Faraday effect in superfluid 3He-B, providing direct evidence for propagating transverse acoustic waves in liquid helium-3, and highlights the role of broken spin-orbit symmetry.

Contribution

It presents the discovery of the acoustic Faraday effect in superfluid 3He-B, confirming a long-standing theoretical prediction and demonstrating the existence of transverse acoustic waves in this quantum fluid.

Findings

Large and observable Faraday rotation in 3He-B

Confirmation of propagating transverse acoustic waves

Agreement between experiment and simulation of acoustic impedance

Abstract

We report the discovery of the acoustic Faraday effect in superfluid 3He-B. The observation of this effect provides the first direct evidence for propagating transverse acoustic waves in liquid 3He, a mode first predicted by Landau in 1957. The Faraday rotation is large and observable because of spontaneously broken spin-orbit symmetry in 3He-B. We compare the experimental observations with a simulation of the transverse acoustic impedance that includes the field-induced circular birefringence of transverse waves.