Diagnosing hyperuniformity in two-dimensional disordered jammed-packings of soft spheres

TL;DR

This study investigates hyperuniformity in two-dimensional disordered jammed packings of soft spheres, addressing experimental challenges and proposing a new methodology for accurate diagnosis using real-space measurements.

Contribution

The paper introduces a packing reconstruction algorithm that accounts for polydispersity and demonstrates improved hyperuniformity detection in experiments and simulations.

Findings

Hyperuniformity can be more accurately diagnosed in real space than reciprocal space.

Particle polydispersity and finite-size effects significantly impact hyperuniformity measurements.

Experimental colloidal packings of soft spheres are confirmed to be hyperuniform.

Abstract

Hyperuniformity characterizes a state of matter for which density fluctuations diminish towards zero at the largest length scales. However, the task of determining whether or not an experimental system is hyperuniform is experimentally challenging due to finite-resolution, noise and sample-size effects that influence characterization measurements. Here we explore these issues, employing video optical microscopy to study hyperuniformity phenomena in disordered two-dimensional jammed packings of soft spheres. Using a combination of experiment and simulation we characterize the detrimental effects of particle polydispersity, image noise, and finite-size effects on the assignment of hyperuniformity, and we develop a methodology that permits improved diagnosis of hyperuniformity from real-space measurements. The key to this improvement is a simple packing reconstruction algorithm that incorporates particle polydispersity to minimize free volume. In addition, simulations show that hyperuniformity can be ascertained more accurately in direct space than in reciprocal space as a result of finite sample-size. Finally, experimental colloidal packings of soft polymeric spheres are shown to be hyperuniform.