Entanglement-enhanced spreading of correlations

Abstract

Starting from a product initial state, equal-time correlations in nonrelativistic quantum lattice models propagate within a light cone-like causal region. The presence of entanglement in the initial state can modify this behaviour, enhancing and accelerating the growth of correlations. In this paper we give a quantitative description, in the form of Lieb-Robinson-type bounds on equal-time correlation functions, of the interplay of dynamics versus. initial entanglement in quantum lattice models out of equilibrium. The bounds are tested against model calculations, and applications to quantum quenches, quantum channels, and Kondo physics are discussed.