Frérot Irénée, Fadel Matteo, Lewenstein Maciej
Institut Néel, CNRS, Grenoble, France.
Department of Physics, ETH Zürich, Zurich, Switzerland.
Rep Prog Phys. 2023 Sep 27;86(11). doi: 10.1088/1361-6633/acf8d7.
We review methods that allow one to detect and characterize quantum correlations in many-body systems, with a special focus on approaches which are scalable. Namely, those applicable to systems with many degrees of freedom, without requiring a number of measurements or computational resources to analyze the data that scale exponentially with the system size. We begin with introducing the concepts of quantum entanglement, Einstein-Podolsky-Rosen steering, and Bell nonlocality in the bipartite scenario, to then present their multipartite generalization. We review recent progress on characterizing these quantum correlations from partial information on the system state, such as through data-driven methods or witnesses based on low-order moments of collective observables. We then review state-of-the-art experiments that demonstrate the preparation, manipulation and detection of highly-entangled many-body systems. For each platform (e.g. atoms, ions, photons, superconducting circuits) we illustrate the available toolbox for state preparation and measurement, emphasizing the challenges that each system poses. To conclude, we present a list of timely open problems in the field.
我们回顾了能够检测和刻画多体系统中量子关联的方法，特别关注可扩展的方法。也就是说，那些适用于具有多个自由度的系统，而无需大量测量或计算资源来分析与系统大小呈指数增长的数据的方法。我们首先介绍二分情形下的量子纠缠、爱因斯坦 - 波多尔斯基 - 罗森引导以及贝尔非定域性的概念，然后呈现它们的多体推广。我们回顾了从系统状态的部分信息来刻画这些量子关联的最新进展，比如通过数据驱动方法或基于集体可观测量低阶矩的见证者。接着，我们回顾了展示高度纠缠多体系统的制备、操控和检测的前沿实验。对于每个平台（例如原子、离子、光子、超导电路），我们阐述了用于状态制备和测量的可用工具箱，强调每个系统所带来的挑战。最后，我们列出了该领域当前亟待解决的开放性问题。
