Time-dependence of correlation functions following a quantum quench

TL;DR

This paper investigates how correlation functions evolve over time after a quantum quench, using boundary critical phenomena and conformal field theory, revealing a quasiparticle propagation picture.

Contribution

It introduces a novel approach to analyze time-dependent correlations post-quench using boundary critical phenomena in higher dimensions and confirms results with solvable models.

Findings

Correlation functions can be derived from boundary critical phenomena methods.

Conformal field theory provides powerful results for one-dimensional systems.

Quasiparticle propagation explains the dynamics of correlations.

Abstract

We show that the time-dependence of correlation functions in an extended quantum system in d dimensions, which is prepared in the ground state of some hamiltonian and then evolves without dissipation according to some other hamiltonian, may be extracted using methods of boundary critical phenomena in d+1 dimensions. For d=1 particularly powerful results are available using conformal field theory. These are checked against those available from solvable models. They may be explained in terms of a picture, valid more generally, whereby quasiparticles, entangled over regions of the order of the correlation length in the initial state, then propagate classically through the system.