Fluctuation of heat current in Josephson junctions

TL;DR

This paper analyzes the statistical fluctuations of heat current in Josephson junctions, revealing how quasiparticle transmission and phase coherence influence heat transport variability.

Contribution

It identifies energy-dependent transmission probabilities and explores phase effects on heat current fluctuations in superconducting junctions.

Findings

Heat transport fluctuations follow the Levitov--Lesovik relation.

In diffusive junctions, heat transport statistics are phase-independent.

Partial phase coherence reintroduces phase dependence in heat fluctuations.

Abstract

We discuss the statistics of heat current between two superconductors at different temperatures connected by a generic weak link. As the electronic heat in superconductors is carried by Bogoliubov quasiparticles, the heat transport fluctuations follow the Levitov--Lesovik relation. We identify the energy-dependent quasiparticle transmission probabilities and discuss the resulting probability density and fluctuation relations of the heat current. We consider multichannel junctions, and find that heat transport in diffusive junctions is unique in that its statistics is independent of the phase difference between the superconductors. Curiously, phase dependence reappears if phase coherence is partially broken.