Supercurrent-induced temperature gradient across a nonequilibrium SNS Josephson junction

TL;DR

This paper demonstrates that a supercurrent can induce a controllable temperature gradient across a nonequilibrium SNS Josephson junction, revealed through tunneling spectroscopy measurements of the electron energy distribution.

Contribution

It introduces a novel method to generate and control temperature gradients in SNS Josephson junctions via supercurrent, using tunneling spectroscopy to observe the effect.

Findings

Supercurrent induces a sharp, odd-in-energy feature in the distribution function.

The temperature gradient can be tuned by adjusting the supercurrent.

The effect is reversible and controllable by supercurrent direction.

Abstract

Using tunneling spectroscopy, we have measured the local electron energy distribution function in the normal part of a superconductor-normal metal-superconductor (SNS) Josephson junction containing an extra lead to a normal reservoir. In the presence of simultaneous supercurrent and injected quasiparticle current, the distribution function exhibits a sharp feature at very low energy. The feature is odd in energy, and odd under reversal of either the supercurrent or the quasiparticle current direction. The feature represents an effective temperature gradient across the SNS Josephson junction that is controllable by the supercurrent.