title: Enhancement of pairwise entanglement via Z2 symmetry breaking.
abstract: We study the effect of symmetry breaking in a quantum phase transition on pairwise entanglement in spin-1/2 models. We give a set of conditions on correlation functions a model has to meet in order to keep the pairwise entanglement unchanged by a parity symmetry breaking. It turns out that all mean-field solvable models do meet this requirement, whereas the presence of strong correlations leads to a violation of this condition. This results in an order-induced enhancement of entanglement, and we report on two examples where this takes place.
authors.affiliation: Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstrasse 2, 30167 Hannover, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Osterloh
authors.forename: Guillaume
authors.initials: G
authors.lastname: Palacios
authors.forename: Simone
authors.initials: S
authors.lastname: Montangero