Nonlocal probes of thermalization in holographic quenches with spectral methods

TL;DR

This paper applies spectral methods to study holographic thermalization in strongly coupled gauge theories, analyzing how local and nonlocal probes reveal the thermalization process after a quench.

Contribution

It introduces a spectral method approach to analyze gravitational collapse and nonlocal probes in holographic quenches, providing new insights into thermalization timescales.

Findings

Nonlocal probes thermalize at length-dependent times.

Longer probes approach the thermalization time of one-point functions.

Different energy scales influence the thermalization process.

Abstract

We describe the application of pseudo-spectral methods to problems of holographic thermal quenches of relevant couplings in strongly coupled gauge theories. We focus on quenches of a fermionic mass term in a strongly coupled N=4 supersymmetric Yang-Mills plasma, and the subsequent equilibration of the system. From the dual gravitational perspective, we study the gravitational collapse of a massive scalar field in asymptotically anti-de Sitter geometry with a prescribed boundary condition for its non-normalizable mode. Access to the full background geometry of the gravitational collapse allows for the study of nonlocal probes of the thermalization process. We discuss the evolution of the apparent and the event horizons, the two-point correlation functions of operators of large conformal dimensions, and the evolution of the entanglement entropy of the system. We compare the thermalization process from the viewpoint of local (the one-point) correlation functions and these nonlocal probes, finding that the thermalization time as measured by the probes is length dependent, and approaches the thermalization time of the one-point function for longer probes. We further discuss how the different energy scales of the problem contribute to its thermalization.