Dissipation controls transport and phase transitions in active fluids: Mobility, diffusion and biased ensembles

TL;DR

This paper explores how energy dissipation influences transport and phase transitions in active fluids, revealing that controlling dissipation can induce clustering or collective motion, offering new insights into active matter behavior.

Contribution

It establishes generic relations between dissipation and transport properties, and demonstrates how tuning dissipation can drive phase transitions in active fluids.

Findings

Local dissipation constrains particle mobility and diffusion.

Low dissipation promotes clustering of particles.

High dissipation leads to collective motion.

Abstract

Active fluids operate by constantly dissipating energy at the particle level to perform a directed motion, yielding dynamics and phases without any equilibrium equivalent. The emerging behaviors have been studied extensively, yet deciphering how local energy fluxes control the collective phenomena is still largely an open challenge. We provide generic relations between the activity-induced dissipation and the transport properties of an internal tracer. By exploiting a mapping between active fluctuations and disordered driving, our results reveal how the local dissipation, at the basis of self-propulsion, constrains internal transport by reducing the mobility and the diffusion of particles. Then, we employ techniques of large deviations to investigate how interactions are affected when varying dissipation. This leads us to shed light on a microscopic mechanism to promote clustering at low dissipation, and we also show the existence of collective motion at high dissipation. Overall, these results illustrate how tuning dissipation provides an alternative route to phase transitions in active fluids.