Nonequilibrium stationary states and equilibrium models with long range interactions

TL;DR

This paper explores the analogy between nonequilibrium steady states and equilibrium models with long-range interactions, using the zeros of a normalization factor to identify phase transitions, exemplified through the asymmetric exclusion process.

Contribution

It demonstrates that the normalization factor in nonequilibrium steady states can be analyzed like an equilibrium partition function, revealing phase transition properties.

Findings

Normalisation factor's zeros indicate phase transitions.

Densities are non-decreasing functions of rates.

Normalisation factor matches an equilibrium partition function.

Abstract

It was recently suggested by Blythe and Evans that a properly defined steady state normalisation factor can be seen as a partition function of a fictitious statistical ensemble in which the transition rates of the stochastic process play the role of fugacities. In analogy with the Lee-Yang description of phase transition of equilibrium systems, they studied the zeroes in the complex plane of the normalisation factor in order to find phase transitions in nonequilibrium steady states. We show that like for equilibrium systems, the ``densities'' associated to the rates are non-decreasing functions of the rates and therefore one can obtain the location and nature of phase transitions directly from the analytical properties of the ``densities''. We illustrate this phenomenon for the asymmetric exclusion process. We actually show that its normalisation factor coincides with an equilibrium partition function of a walk model in which the ``densities'' have a simple physical interpretation.