Dissipative Currents in Superfluid 3He Weak Links

TL;DR

This paper models the current-pressure relationship in superfluid 3He-B weak links, revealing nonlinear behavior and dissipation effects due to spin wave radiation, aligning with experimental observations.

Contribution

It adapts the multiple Andreev reflections theory to superfluid 3He-B and incorporates texture oscillations and spin wave radiation effects.

Findings

Nonlinear current-pressure relation in superfluid 3He-B weak links

Additional dissipation from spin wave radiation at small biases

Quantitative agreement with experimental measurements

Abstract

We calculate the current-pressure relation for pinholes connecting two volumes of bulk superfluid 3He-B. The theory of multiple Andreev reflections, adapted from superconducting weak links, leads to a nonlinear dependence of the dc current on pressure bias. In arrays of pinholes one has to take into account oscillations of the texture at the Josephson frequency. The associated radiation of spin waves from the junction leads to an additional dissipative current at small biases, in quantitative agreement with measurements.