Search for Hyperuniformity in Mechanically Stable Packings of Frictionless Disks Above Jamming

TL;DR

This study investigates whether hyperuniformity exists in mechanically stable packings of frictionless disks above the jamming point, finding it persists only up to a finite length scale and depends on the preparation protocol.

Contribution

It demonstrates that hyperuniformity in jammed packings is not universal at the jamming transition and is influenced by the configuration generation method.

Findings

Hyperuniformity persists only up to a finite length scale.

The finite length scale remains as the system approaches jamming.

Hyperuniformity's presence depends on the packing protocol used.

Abstract

We numerically simulate mechanically stable packings of soft-core, frictionless, bidisperse disks in two dimensions, above the jamming packing fraction phi_J. For configurations with a fixed isotropic global stress tensor, we investigate the fluctuations of the local packing fraction phi(r) to test whether such configurations display the hyperuniformity that has been claimed to exist exactly at phi_J. For our configurations, generated by a rapid quench protocol, we find that hyperuniformity persists only out to a finite length scale, and that this length scale appears to remain finite as the system stress decreases towards zero, i.e. towards the jamming transition. Our result suggests that the presence of hyperuniformity at jamming may be sensitive to the specific protocol used to construct the jammed configurations.