# Quantum Quench and Scaling of Entanglement Entropy

## TL;DR

This paper investigates how entanglement entropy in a harmonic chain scales during a mass quench crossing critical points, revealing size independence at large subsystem sizes and connecting to known quench scaling laws.

## Contribution

It provides an exactly solvable model demonstrating entanglement entropy scaling behavior during a mass quench crossing critical points.

## Key findings

- Entanglement entropy becomes size-independent for large subsystems.
- Results align with Kibble-Zurek scaling for slow quenches.
- Supports 'fast quench scaling' in certain regimes.

## Abstract

Global quantum quench with a finite quench rate which crosses critical points is known to lead to universal scaling of correlation functions as functions of the quench rate. In this work, we explore scaling properties of the entanglement entropy of a subsystem in a harmonic chain during a mass quench which asymptotes to finite constant values at early and late times and for which the dynamics is exactly solvable. When the initial state is the ground state, we find that for large enough subsystem sizes the entanglement entropy becomes independent of size. This is consistent with Kibble-Zurek scaling for slow quenches, and with recently discussed "fast quench scaling" for quenches fast compared to physical scales, but slow compared to UV cutoff scales.