Violation of the fluctuation-dissipation theorem in glassy systems: basic notions and the numerical evidence

TL;DR

This review explores the violations of the fluctuation-dissipation theorem in glassy systems, focusing on the quasi-FDT, supported by numerical simulations across various models and experimental evidence.

Contribution

It provides a comprehensive overview of the numerical and theoretical evidence for the quasi-FDT in diverse glassy systems, bridging basic concepts and recent findings.

Findings

Numerical simulations support the existence of QFDT in glassy systems.

Analytical tools from exactly solvable models elucidate FDT violations.

Experimental evidence aligns with theoretical predictions of QFDT.

Abstract

This review reports on the research done during the past years on violations of the fluctuation-dissipation theorem (FDT) in glassy systems. It is focused on the existence of a quasi-fluctuation-dissipation theorem (QFDT) in glassy systems and the currently supporting knowledge gained from numerical simulation studies. It covers a broad range of non-stationary aging and stationary driven systems such as structural-glasses, spin-glasses, coarsening systems, ferromagnetic models at criticality, trap models, models with entropy barriers, kinetically constrained models, sheared systems and granular media. The review is divided into four main parts: 1) An introductory section explaining basic notions related to the existence of the FDT in equilibrium and its possible extension to the glassy regime (QFDT), 2) A description of the basic analytical tools and results derived in the framework of some exactly solvable models, 3) A detailed report of the current evidence in favour of the QFDT and 4) A brief digression on the experimental evidence in its favour. This review is intended for inexpert readers who want to learn about the basic notions and concepts related to the existence of the QFDT as well as for the more expert readers who may be interested in more specific results.