title: Optimal correlations in many-body quantum systems.
abstract: Information and correlations in a quantum system are closely related through the process of measurement. We explore such relation in a many-body quantum setting, effectively bridging between quantum metrology and condensed matter physics. To this aim we adopt the information-theory view of correlations and study the amount of correlations after certain classes of positive-operator-valued measurements are locally performed. As many-body systems, we consider a one-dimensional array of interacting two-level systems (a spin chain) at zero temperature, where quantum effects are most pronounced. We demonstrate how the optimal strategy to extract the correlations depends on the quantum phase through a subtle interplay between local interactions and coherence.
authors.affiliation: CNR-MATIS-IMM and Dipartimento di Fisica e Astronomia, Università di Catania, C/O ed. 10, viale A. Doria 6, I-95125 Catania, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Amico
authors.forename: D
authors.initials: D
authors.lastname: Rossini
authors.forename: A
authors.initials: A
authors.lastname: Hamma
authors.forename: V E
authors.initials: VE
authors.lastname: Korepin