Inhomogeneous Quantum Quenches

TL;DR

This paper investigates inhomogeneous quantum quenches in conformal and free field theories, deriving general evolution expressions and revealing non-diffusive dynamics characterized by quasiparticle propagation.

Contribution

It provides the first analytical expressions for energy flow, correlations, and entanglement entropy in inhomogeneous quantum quenches within conformal and free field models.

Findings

Agreement between conformal and free field results in overlapping regimes

Evolution is non-diffusive, driven by quasiparticles

Results enhance understanding of thermalization in inhomogeneous quantum systems

Abstract

We study the problem of a quantum quench in which the initial state is the ground state of an inhomogeneous hamiltonian, in two different models, conformal field theory and ordinary free field theory, which are known to exhibit thermalisation of finite regions in the homogeneous case. We derive general expressions for the evolution of the energy flow and correlation functions, as well as the entanglement entropy in the conformal case. Comparison of the results of the two approaches in the regime of their common validity shows agreement up to a point further discussed. Unlike the thermal analogue, the evolution in our problem is non-diffusive and can be physically interpreted using an intuitive picture of quasiparticles emitted from the initial time hypersurface and propagating semiclassically.