Thermal relaxation asymmetry persists under inertial effects

TL;DR

This paper algebraically proves that thermal relaxation asymmetry, where heating is faster than cooling, persists across both overdamped and underdamped dynamics, revealing complex phase-space relaxation behaviors.

Contribution

It extends the understanding of thermal relaxation asymmetry from overdamped to underdamped dynamics, highlighting the role of velocity degrees of freedom and interpretation of temperature quenches.

Findings

Thermal relaxation asymmetry persists in underdamped dynamics.

Velocity degrees of freedom influence free energy contributions.

Overdamped limit reveals non-trivial effects of temperature quench interpretations.

Abstract

We algebraically prove the asymmetry in thermal relaxation in phase space in the entire range from overdamped dynamics to underdamped dynamics. We show that for the same setup as for overdamped dynamics, even in the more general case of phase-space relaxation, i.e., underdamped dynamics, far-from-equilibrium heating is faster than cooling. Upon isolating the relevant relaxational contribution to the entropy production, we find that the asymmetry persist for underdamped dynamics that are linearly driven out of equilibrium. The coupling of positions and velocities emerging in this generalization further underscores, in a striking manner, the intricate dynamics of such thermal relaxation processes that do not pass through local equilibria. Investigating the overdamped limit, our generalized approach reveals, interestingly, that an excess free energy contribution from the velocity degrees of freedom does not trivially vanish in the overdamped limit, but is instead affected by the precise interpretation of temperature quenches in overdamped systems.