Isolated Non-Equilibrium Systems in Contact

TL;DR

This paper studies a solvable model of non-equilibrium steady states with energy conservation, revealing how time-reversal asymmetry affects detailed balance, ergodicity, and effective temperature, with implications for entropy and energy flow.

Contribution

It introduces a solvable model for non-equilibrium steady states, analyzing effective temperature and entropy behavior when systems are in contact.

Findings

Effective temperature controls energy flow between systems.

Contact can lead to a decrease in total entropy.

Systems may not reach the same temperature despite contact.

Abstract

We investigate a solvable model for energy conserving non-equilibrium steady states. The time-reversal asymmetry of the dynamics leads to the violation of detailed balance and to ergodicity breaking, as manifested by the presence of dynamically inaccessible states. Two such systems in contact do not reach the same effective temperature if standard definitions are used. However, we identify the effective temperature that controls energy flow. Although this operational temperature does reach a common value upon contact, the total entropy of the joint system can decrease.