Thermodynamic efficiency of self-organisation in nonequilibrium steady states

TL;DR

This paper investigates the thermodynamic efficiency of self-organization in nonequilibrium steady states, extending information-theoretic measures to active matter systems and analyzing efficiency behavior at phase transitions.

Contribution

It introduces an extended framework for entropy reduction and efficiency measurement in nonequilibrium systems, applied to active Ising models.

Findings

Efficiency maximizes at phase transitions.

Thermodynamic and inferential efficiencies diverge out of equilibrium.

Efficiency gap indicates distance from equilibrium.

Abstract

Active matter generates order or patterns through nonequilibrium dynamics. An open research challenge is to determine how efficiently a nonequilibrium self-organising system can convert consumed energy into macroscopic order. We study an information-theoretic quantity that directly addresses this challenge by estimating the entropy reduction induced by a small control-parameter perturbation, relative to the generalised work required for the perturbation. This quantity has previously been considered mainly in an equilibrium or near-equilibrium context, and here we extend this framework and apply it to two nonequilibrium self-organising systems: persistent and active Ising models. We observe that the thermodynamic efficiency of nonequilibrium systems maximises at phase transitions, as in equilibrium systems. Furthermore, we compare thermodynamic efficiency and inferential efficiency across control parameters. While these two quantities are equal in equilibrium as a consequence of the fluctuation-dissipation theorem, we report that they diverge out of equilibrium, and the gap reflects how far the system is from equilibrium.