Dynamical origin of spontaneous symmetry breaking in a field-driven nonequilibrium system

TL;DR

This paper investigates how spontaneous symmetry breaking occurs in a one-dimensional driven two-species system, revealing that an amplification of fluctuations leads to symmetry breaking throughout the parameter space where it exists.

Contribution

It provides a detailed analysis and proof that symmetry breaking results from an amplification mechanism of fluctuations in a specific nonequilibrium model.

Findings

Symmetry breaking occurs despite symmetric microscopic dynamics.

The amplification mechanism explains the stability of the broken symmetry state.

The proof applies throughout the entire parameter region with broken symmetry.

Abstract

A one-dimensional driven two-species model with parallel sublattice update and open boundaries is considered. Although the microscopic many-body dynamics is symmetric with respect to the two species and interactions are short-ranged, there is a region in parameter space with broken symmetry in the steady state. The sublattice update is deterministic in the bulk and allows for a detailed analysis of the relaxation dynamics, so that symmetry breaking can be shown to be the result of an amplification mechanism of fluctuations. In contrast to previously considered models, this leads to a proof for spontaneous symmetry breaking which is valid throughout the whole region in parameter space with a symmetry broken steady state.