Out-of-Equilibrium Fluctuation-Dissipation Bounds

TL;DR

This paper establishes a universal inequality linking charge current and fluctuations in non-interacting electronic conductors out of equilibrium, offering new bounds that surpass traditional fluctuation-dissipation relations and impact heat engine efficiency.

Contribution

It introduces a general fluctuation-dissipation bound valid for out-of-equilibrium quantum conductors, extending beyond classical relations and applicable near thermovoltage.

Findings

Bound saturates at high temperature bias

Limits heat engine output power based on fluctuations

Provides stronger constraints when quantum effects break thermodynamic uncertainty relations

Abstract

We prove a general inequality between the charge current and its fluctuations valid for any non-interacting coherent electronic conductor and for any stationary out-of-equilibrium condition, thereby going beyond established fluctuation-dissipation relations. The developed fluctuation-dissipation bound saturates at large temperature bias and reveals additional insight for heat engines, since it limits the output power by power fluctuations. It is valid when the thermodynamic uncertainty relations break down due to quantum effects and provides stronger constraints close to thermovoltage.