# Thermalization after holographic bilocal quench

## TL;DR

This paper investigates the process of thermalization in a (1+1)-dimensional holographic CFT after creating two high-energy excitations, using the dual gravity picture of black hole formation from particle collision, and analyzes entanglement and correlation evolution.

## Contribution

It provides a detailed holographic analysis of entanglement propagation and memory loss in a bilocal quench scenario, highlighting distinctions from other models and the role of black hole interior dynamics.

## Key findings

- Entanglement propagates along a sharp light cone.
- Memory of initial state is lost during equilibration.
- Linear growth of entanglement is universal and related to black hole interior.

## Abstract

We study thermalization in the holographic (1+1)-dimensional CFT after simultaneous generation of two high-energy excitations in the antipodal points on the circle. The holographic picture of such quantum quench is the creation of BTZ black hole from a collision of two massless particles. We perform holographic computation of entanglement entropy and mutual information in the boundary theory and analyze their evolution with time. We show that equilibration of the entanglement in the regions which contained one of the initial excitations is generally similar to that in other holographic quench models, but with some important distinctions. We observe that entanglement propagates along a sharp effective light cone from the points of initial excitations on the boundary. The characteristics of entanglement propagation in the global quench models such as entanglement velocity and the light cone velocity also have a meaning in the bilocal quench scenario. We also observe the loss of memory about the initial state during the equilibration process. We find that the memory loss reflects on the time behavior of the entanglement similarly to the global quench case, and it is related to the universal linear growth of entanglement, which comes from the interior of the forming black hole. We also analyze general two-point correlation functions in the framework of the geodesic approximation, focusing on the study of the late time behavior.