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 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.

5 pages, 5 figures + supplementary material. To be published in PRL

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• Global quantum correlations in finite-size spin chains
• Quantum discord in the ground state of spin chains
• Exact dynamics of quantum correlations of two qubits coupled to bosonic baths
• Witnessing Entanglement and Quantum Correlations in Condensed Matter: A Review
• Magnetic quantum correlation in the 1D transverse-field XXZ model
• Adiabatic freezing of long-range quantum correlations in spin chains
• Quantum sensing of even- versus odd-body interactions
• Tomography of a single-atom-resolved detector in the presence of shot-to-shot number fluctuations