Microcanonical quasi-stationarity of long-range interacting systems in contact with a heat bath

TL;DR

This paper investigates the nonequilibrium dynamics of long-range interacting systems in contact with a heat bath, revealing a sequence of quasi-stationary states before reaching thermal equilibrium, with implications for experimental control.

Contribution

It demonstrates the microcanonical quasi-stationarity in long-range systems coupled to a heat bath and compares Langevin and Hamiltonian thermostats, providing insights into controlling such systems.

Findings

Systems exhibit Vlasov quasi-stationary states before thermalization.

Langevin and Hamiltonian reservoirs are equivalent in describing the dynamics.

Identification of parameters influencing quasi-stationary lifetimes.

Abstract

On the basis of analytical results and molecular dynamics simulations we clarify the nonequilibrium dynamics of a long-range interacting system in contact with a heat bath. For small couplings with the bath, we show that the system can first be trapped in a Vlasov quasi-stationary state, then a microcanonical one follows, and finally canonical equilibrium is reached at the bath temperature. We compare a Langevin mesoscopic thermostat with Hamiltonian reservoirs microscopically coupled with the system and demonstrate the equivalence of the two descriptions. Our identification of the parameters determining the quasi-stationary lifetimes could be exploited to control experimental systems such as the Free Electron Laser, in the presence of external noise or inherent imperfections.