Intermittency of glassy relaxation and the emergence of a non-equilibrium spontaneous measure in the aging regime

TL;DR

This paper investigates heat exchange in aging non-equilibrium systems, revealing a spontaneous intermittent process characterized by an exponential PDF tail, which relates to an effective temperature measurable via fluctuation theorems.

Contribution

It introduces a novel description of spontaneous heat exchange in aging systems using a PDF with an exponential tail, linking it to an effective temperature and fluctuation theorem.

Findings

Identification of a spontaneous intermittent heat exchange process

Derivation of an exponential tail in the PDF of heat events

Establishment of a relation between tail parameter and effective temperature

Abstract

We consider heat exchange processes between non-equilibrium aging systems (in their activated regime) and the thermal bath in contact. We discuss a scenario where two different heat exchange processes concur in the overall heat dissipation: a stimulated fast process determined by the temperature of the bath and a spontaneous intermittent process determined by the fact that the system has been prepared in a non-equilibrium state. The latter is described by a probability distribution function (PDF) that has an exponential tail of width given by a parameter $\lambda$, and satisfies a fluctuation theorem (FT) governed by that parameter. The value of $\lambda$ is proportional to the so-called effective temperature, thereby providing a practical way to experimentally measure it by analyzing the PDF of intermittent events.