CNR-MATIS-IMM and Dipartimento di Fisica e Astronomia, Università di Catania, C/O ed. 10, viale A. Doria 6, I-95125 Catania, Italy.
Phys Rev Lett. 2012 Jun 15;108(24):240503. doi: 10.1103/PhysRevLett.108.240503.
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.
信息和关联在量子系统中通过测量过程密切相关。我们在多体量子环境中探索这种关系，有效地将量子计量学和凝聚态物理联系起来。为此，我们采用相关性的信息论观点，并研究在局部执行某些类正算子值测量后相关性的数量。作为多体系统，我们考虑零温度下相互作用的二维系统（自旋链）的一维阵列，其中量子效应最为明显。我们展示了如何通过局部相互作用和相干性之间的微妙相互作用，依赖于量子相位的最优策略来提取相关性。
