Giant density fluctuations in locally hyperuniform states

TL;DR

This paper reveals a novel state in active matter where giant density fluctuations coexist with hyperuniformity, driven by contact-conditioned activity, expanding understanding of non-equilibrium systems.

Contribution

It introduces a new class of active matter states combining hyperuniformity and giant fluctuations, linked to contact-dependent activity in nematic systems.

Findings

Coexistence of hyperuniformity and giant density fluctuations.

Mechanism involves activity triggered by local contacts.

Potential for diverse phenomena in contact-driven active matter.

Abstract

Systems driven far from equilibrium may exhibit anomalous density fluctuations: active matter with orientational order display giant density fluctuations at large scale, while systems of interacting particles close to an absorbing phase transition may exhibit hyperuniformity, suppressing large-scale density fluctuations. We show that these seemingly incompatible phenomena can coexist in nematically ordered active systems, provided activity is conditioned to particle contacts. We characterize this unusual state of matter and unravel the underlying mechanisms simultaneously leading to spatially enhanced (on large length scales) and suppressed (on intermediate length scales) density fluctuations. Our work highlights the potential for a rich phenomenology in active matter systems in which particles' activity is triggered by their local environment, and calls for a more systematic exploration of absorbing phase transitions in orientationally-ordered particle systems.