Optimal correlations in many-body quantum systems

TL;DR

This paper investigates how measurement-induced correlations in a one-dimensional quantum spin chain depend on the quantum phase, revealing the interplay between local interactions and coherence in many-body systems.

Contribution

It introduces an information-theoretic approach to analyze measurement-induced correlations in many-body quantum systems, connecting quantum metrology and condensed matter physics.

Findings

Optimal measurement strategies vary with quantum phase.

Correlations are influenced by local interactions and coherence.

Quantum effects are most pronounced at zero temperature.

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 system 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.