Variational formula for experimental determination of high-order correlations of current fluctuations in driven systems

TL;DR

This paper introduces a variational formula enabling experimental determination of high-order current fluctuation correlations in driven systems, avoiding direct fluctuation measurements through a theoretical derivation and numerical validation.

Contribution

It presents a novel variational formula for experimentally accessing cumulant generating functions of current fluctuations without direct fluctuation measurements.

Findings

The formula is derived phenomenologically based on fluctuation relations and additivity.

Numerical experiments demonstrate the practical effectiveness of the formula.

The approach simplifies experimental procedures for studying current fluctuations.

Abstract

For Brownian motion of a single particle subject to a tilted periodic potential on a ring, we propose a formula for experimentally determining the cumulant generating function of time-averaged current without measurements of current fluctuations. We first derive this formula phenomenologically on the basis of two key relations: a fluctuation relation associated with Onsager's principle of the least energy dissipation in a sufficiently local region and an additivity relation by which spatially inhomogeneous fluctuations can be properly considered. We then derive the formula without any phenomenological assumptions. We also demonstrate its practical advantage by numerical experiments.