Entanglement and correlation functions following a local quench: a conformal field theory approach

TL;DR

This paper uses conformal field theory to analyze the dynamics of entanglement and correlation functions in a one-dimensional quantum system after a local quench, revealing quasiparticle propagation as a key mechanism.

Contribution

It provides a conformal field theory framework for understanding entanglement and correlations after a local quench in 1D quantum systems, emphasizing quasiparticle propagation.

Findings

Entanglement entropy evolves according to quasiparticle emission.

Correlation functions show light-cone spreading.

Results are consistent with a semiclassical quasiparticle picture.

Abstract

We show that the dynamics resulting from preparing a one-dimensional quantum system in the ground state of two decoupled parts, then joined together and left to evolve unitarily with a translational invariant Hamiltonian (a local quench), can be described by means of quantum field theory. In the case when the corresponding theory is conformal, we study the evolution of the entanglement entropy for different bi-partitions of the line. We also consider the behavior of one- and two-point correlation functions. All our findings may be explained in terms of a picture, that we believe to be valid more generally, whereby quasiparticles emitted from the joining point at the initial time propagate semiclassically through the system.