Fluctuation-dissipation relations far from equilibrium

TL;DR

This paper extends fluctuation-dissipation relations to certain out-of-equilibrium systems within stochastic thermodynamics, showing an equilibrium-like FDR for internally equilibrated currents under specific conditions.

Contribution

It demonstrates that an equilibrium-like fluctuation-dissipation relation applies to internally equilibrated currents when perturbations affect only relevant microscopic transitions.

Findings

Equilibrium-like FDR holds for certain out-of-equilibrium currents.

Conditions for the validity of the FDR are discussed.

Application to nano-sized electronic devices illustrates practical relevance.

Abstract

Near equilibrium, where all currents of a system vanish on average, the fluctuation-dissipation relation (FDR) connects a current's spontaneous fluctuations with its response to perturbations of the conjugate thermodynamic force. Out of equilibrium, fluctuation-response relations generally involve additional nondissipative contributions. Here, in the framework of stochastic thermodynamics, we show that an equilibrium-like FDR holds for internally equilibrated currents, if the perturbing conjugate force only affects the microscopic transitions that contribute to the current. We discuss the physical requirements for the validity of our result and apply it to nano-sized electronic devices.