Memory formation in jammed hard spheres

TL;DR

This paper investigates memory effects in jammed hard spheres, demonstrating their thermodynamic and dimensional robustness, and uncovers a second memory type linked to a Gardner-like transition during jamming.

Contribution

It provides the first simulation-based evidence of thermodynamic and dimensional robustness of memory phenomena in jammed spheres and identifies a new Gardner-like memory transition.

Findings

Memory effects are thermodynamically robust.

Memory effects are dimensionally robust.

A second Gardner-like memory transition is discovered.

Abstract

Liquids equilibrated below an onset density share similar inherent states, while above that density their inherent states markedly differ. Although this phenomenon was first reported in simulations over 20 years ago, the physical origin of this memory remains controversial. Its absence from mean-field descriptions, in particular, has long cast doubt on its thermodynamic relevance. Motivated by a recent theoretical proposal, we reassess the onset phenomenology in simulations using a fast hard sphere jamming algorithm and find it both thermodynamically and dimensionally robust. Remarkably, we also uncover a second type of memory associated with a Gardner-like change in behavior along the jamming algorithm.