The distribution of work performed on a NIS junction

TL;DR

This paper introduces an experimental method to measure work and heat in a NIS junction under voltage change, linking it to two-level systems and enabling testing of fluctuation relations.

Contribution

It presents a novel experimental setup and theoretical analysis for measuring work and heat in NIS junctions, connecting their dynamics to two-level systems for exact calculations.

Findings

Work and heat can be experimentally measured in NIS junctions.

Work distribution is non-Gaussian, with fluctuations characterized.

The setup allows testing of the Crooks-Tasaki fluctuation relation.

Abstract

We propose an experimental setup to measure the work performed in a normal-metal/insulator/superconducting (NIS) junction, subjected to a voltage change and in contact with a thermal bath. We compute the performed work and argue that the associated heat release can be measured experimentally. Our results are based on an equivalence between the dynamics of the NIS junction and that of an assembly of two-level systems subjected to a circularly polarised field, for which we can determine the work-characteristic function exactly. The average work dissipated by the NIS junction, as well as its fluctuations, are determined. From the work characteristic function, we also compute the work probability-distribution and show that it does not have a Gaussian character. Our results allow for a direct experimental test of the Crooks-Tasaki fluctuation relation.