Carvacho Gonzalo, Graffitti Francesco, D'Ambrosio Vincenzo, Hiesmayr Beatrix C, Sciarrino Fabio
Dipartimento di Fisica, Sapienza Università di Roma, I-00185, Roma, Italy.
University of Vienna, Faculty of Physics, Boltzmanngasse 5, 1090, Vienna, Austria.
Sci Rep. 2017 Oct 16;7(1):13265. doi: 10.1038/s41598-017-13124-6.
Greenberger-Horne-Zeilinger (GHZ) states and their mixtures exhibit fascinating properties. A complete basis of GHZ states can be constructed by properly choosing local basis rotations. We demonstrate this experimentally for the Hilbert space [Formula: see text] by entangling two photons in polarization and orbital angular momentum. Mixing GHZ states unmasks different entanglement features based on their particular local geometrical connectedness. In particular, a specific GHZ state in a complete orthonormal basis has a "twin" GHZ state for which equally mixing leads to full separability in opposition to any other basis-state. Exploiting these local geometrical relations provides a toolbox for generating specific types of multipartite entanglement, each providing different benefits in outperforming classical devices. Our experiment investigates these GHZ's properties exploiting the HMGH framework which allows us to study the geometry for the different depths of entanglement in our system and showing a good stability and fidelity thus admitting a scaling in degrees of freedom and advanced operational manipulations.
格林伯格 - 霍恩 - 泽林格（GHZ）态及其混合态展现出迷人的特性。通过适当选择局部基旋转，可以构建GHZ态的完备基。我们通过在偏振和轨道角动量方面纠缠两个光子，在希尔伯特空间[公式：见正文]中对此进行了实验演示。混合GHZ态基于其特定的局部几何连通性揭示了不同的纠缠特征。特别地，在一个完备正交基中的特定GHZ态有一个“孪生”GHZ态，对于该“孪生”态，同等混合会导致完全可分离，这与任何其他基态情况相反。利用这些局部几何关系提供了一个生成特定类型多体纠缠的工具箱，每种多体纠缠在超越经典器件方面都有不同的优势。我们的实验利用HMGH框架研究这些GHZ态的特性，该框架使我们能够研究系统中不同纠缠深度的几何结构，并显示出良好的稳定性和保真度，从而允许在自由度上进行扩展以及进行先进的操作操控。
