Strong Correlations Between Fluctuations and Response in Aging Transport

TL;DR

This paper reveals that, in aging transport systems, correlations between fluctuations and responses persist over time in the aging phase, with a theoretical relation linking these correlations to fractional diffusion.

Contribution

It provides an exact analytical theory and numerical simulations showing persistent correlations in aging transport models, connecting fluctuations to response behavior.

Findings

Finite correlations in aging phase even as $t_a \to \infty$

Zero correlations in non-aging phase in the same limit

Relation between correlations and fractional diffusion coefficient

Abstract

Once the problem of ensemble averaging is removed, correlations between the response of a single molecule to an external driving field $F$, with the history of fluctuations of the particle, become detectable. Exact analytical theory for the continuous time random walk and numerical simulations for the quenched trap model give the behaviors of the correlation between fluctuations of the displacement in the aging period $(0,t_a)$, and the response to bias switched on at time $t_a$. In particular in the dynamical phase where the models exhibit aging we find finite correlations even in the asymptotic limit $t_a \to \infty$, while in the non-aging phase the correlations are zero in the same limit. Linear response theory gives a simple relation between these correlations and the fractional diffusion coefficient.