Disordered collective motion in dense assemblies of persistent particles

TL;DR

This study investigates how size diversity in active particles influences collective motion and phase transitions in dense, nonequilibrium systems, revealing stabilization of homogeneous states and complex dynamics.

Contribution

It demonstrates that polydispersity stabilizes active liquids at high persistence and uncovers new nonequilibrium behaviors and transitions in dense active matter.

Findings

Polydispersity stabilizes homogeneous active liquids at large persistence.

Active fluids undergo a nonequilibrium glass transition at high density.

Different regimes of collective motion emerge depending on persistence.

Abstract

We explore the emergence of nonequilibrium collective motion in disordered non-thermal active matter when persistent motion and crowding effects compete, using simulations of a two-dimensional model of size polydisperse self-propelled particles. In stark contrast with monodisperse systems, we find that polydispersity stabilizes a homogeneous active liquid at arbitrary large persistence times, characterized by remarkable velocity correlations and irregular turbulent flows. For all persistence values, the active fluid undergoes a nonequilibrium glass transition at large density. This is accompanied by collective motion, whose nature evolves from near-equilibrium spatially heterogeneous dynamics at small persistence, to a qualitatively different intermittent dynamics when persistence is large. This latter regime involves a complex time evolution of the correlated displacement field