Thermodynamic uncertainty relations in superconducting junctions

Abstract

It has recently been predicted that the thermodynamic uncertainty relation (TUR), which expresses a trade-off between the amount of dissipation and the absence of fluctuations, can be violated in the context of charge transport in normal quantum conductors. However, the required conditions are difficult to meet, and no experimental violation has been reported yet in mesoscopic quantum transport experiments. Here, we predict that TUR can be largely violated in superconducting (SC) contacts without introducing an energy dependency in the normal transmission coefficient. This violation originates from the coexistence of tunneling processes involving different numbers of transmitted charges, namely, quasiparticle tunneling and Andreev reflections. The SC junctions invoked here have been fabricated by many groups and constitute an ideal platform to demonstrate TUR breaking in charge transport experiments.