Effect of rare events on out of equilibrium relaxation

TL;DR

This paper investigates how rare particle jumps influence the relaxation process in an out-of-equilibrium granular medium, combining experimental and numerical approaches to reveal their critical role despite their low probability.

Contribution

It provides the first combined experimental and numerical analysis showing the importance of rare jumps in out-of-equilibrium relaxation.

Findings

Rare jumps significantly affect system relaxation.

Jumps are similar to those in glasses and colloids.

Inhibiting jumps alters relaxation dynamics.

Abstract

This letter reports experimental and numerical results on particle dynamics in an out-of-equilibrium granular medium. We observed two distinct types of grain motion: the well known cage motion, during which a grain is always surrounded by the same neighbors, and low probability "jumps", during which a grain moves significantly more relative to the others. These observations are similar to the results obtained for other out-of-equilibrium systems (glasses, colloidal systems, etc.). Although such jumps are extremely rare, by inhibiting them in numerical simulations we demonstrate that they play a significant role in the relaxation of out-of-equilibrium systems