Negative autocorrelations of disorder strongly suppress thermally activated particle motion in short-correlated quenched Gaussian disorder potentials

TL;DR

This paper investigates how negative autocorrelations in short-range quenched Gaussian disorder potentials significantly alter the tail of the potential barrier distribution, thereby exponentially affecting the mean escape time of particles.

Contribution

It demonstrates that negative autocorrelations in disorder potentials lead to a substantial increase in escape times, revealing a new effect not captured by previous models with monotonic autocovariances.

Findings

Negative autocorrelations increase the tail of the potential barrier distribution.

Autocovariance shape drastically changes the mean escape time.

Exponential variation in escape time due to disorder autocorrelation properties.

Abstract

We evaluate the mean escape time of overdamped particles over potential barriers in short-correlated quenched Gaussian disorder potentials in one dimension at low temperature. The thermally activated escape is very sensitive to the form of the \emph{tail} of the potential barrier probability distribution. We evaluate this tail by using the optimal fluctuation method. For monotone decreasing autocovariances we reproduce the tail obtained by Lopatin and Vinokur (2001). However, for nonmonotonic autocovariances of the disorder potential we show that the tail changes. It is much higher when the disorder potential exhibits negative autocorrelations, and it is much lower when the autocovariance is nonmonotonic but everywhere positive. This leads to an \emph{exponential} increase or decrease, respectively, of the mean escape time.