Microreversibility, nonequilibrium current fluctuations, and response theory

TL;DR

This paper explores how microreversibility imposes symmetry relations on current fluctuations and response coefficients in open systems, enabling a systematic reduction in the number of independent quantities needed to characterize transport properties.

Contribution

It demonstrates that time-reversal symmetry relations significantly reduce the complexity of measuring or computing transport properties in nonequilibrium systems.

Findings

Symmetry relations connect cumulants and response coefficients at all orders.

The number of independent quantities is reduced by approximately half for high-order measurements.

Systematic framework for analyzing current fluctuations in open systems.

Abstract

Microreversibility rules the fluctuations of the currents flowing across open systems in nonequilibrium (or equilibrium) steady states. As a consequence, the statistical cumulants of the currents and their response coefficients at arbitrary orders in the deviations from equilibrium obey time-reversal symmetry relations. It is shown that these relations allow us to systematically reduce the amount of independent quantities that need to be measured experimentally or computed theoretically in order to fully characterize the linear and nonlinear transport properties of general open systems. This reduction is shown to approach one half for quantities of arbitrarily high orders.