Thermodynamic uncertainty relations in superconducting junctions

TL;DR

This paper demonstrates significant violations of thermodynamic uncertainty relations in superconducting junctions, revealing new transport phenomena that could enhance the efficiency of quantum thermal machines.

Contribution

It introduces the concept of TUR violations in superconducting reservoirs and identifies multiple Andreev reflection as the key mechanism behind these violations.

Findings

Large TUR violations observed with superconducting reservoirs

Multiple Andreev reflection causes TUR breakdowns

Potential for low dissipation quantum thermal machines

Abstract

Quantum conductors attached to metallic reservoirs have been demonstrated to overcome the thermodynamic uncertainty relation (TUR), a trade-off relation between the amount of dissipation and the absence of charge and heat current fluctuations. Here, we report large TUR violations when superconducting reservoirs replace metallic ones. The coexistence of different transport processes, namely (multiple) Andreev reflection, where electrons and their retro-reflected holes create Cooper pairs, in addition to the normal quasiparticle transport is identified as the source for such TUR breakdowns. The large TUR violation is a remarkable advantage for building low dissipative and highly stable quantum thermal machines.