Collapse and Revival in Holographic Quenches

TL;DR

This paper investigates holographic models of quantum quenches in finite systems, revealing conditions for revivals and the emergence of collapse and revival timescales, with implications for understanding non-equilibrium dynamics.

Contribution

It compares holographic evolution on a circle and a sphere, identifying conditions for revivals and analyzing the timescales involved, which was not previously explored in this context.

Findings

Revivals occur in both circle and sphere geometries under certain conditions.

Two distinct timescales, collapse and revival, are identified and depend on initial energy density.

The ratio of these timescales mirrors experimental observations of collapse and revival phenomena.

Abstract

We study holographic models related to global quantum quenches in finite size systems. The holographic set up describes naturally a CFT, which we consider on a circle and a sphere. The enhanced symmetry of the conformal group on the circle motivates us to compare the evolution in both cases. Depending on the initial conditions, the dual geometry exhibits oscillations that we holographically interpret as revivals of the initial field theory state. On the sphere, this only happens when the energy density created by the quench is small compared to the system size. However on the circle considerably larger energy densities are compatible with revivals. Two different timescales emerge in this latter case. A collapse time, when the system appears to have dephased, and the revival time, when after rephasing the initial state is partially recovered. The ratio of these two times depends upon the initial conditions in a similar way to what is observed in some experimental setups exhibiting collapse and revivals.