Lo Hsin-Pin, Li Che-Ming, Yabushita Atsushi, Chen Yueh-Nan, Luo Chih-Wei, Kobayashi Takayoshi
Department of Electrophysics, National Chiao-Tung University, Hsinchu City 300, Taiwan.
Department of Engineering Science, National Cheng-Kung University, Tainan City 701, Taiwan.
Sci Rep. 2016 Feb 26;6:22088. doi: 10.1038/srep22088.
Quantum correlations between spatially separated parts of a d-dimensional bipartite system (d ≥ 2) have no classical analog. Such correlations, also called entanglements, are not only conceptually important, but also have a profound impact on information science. In theory the violation of Bell inequalities based on local realistic theories for d-dimensional systems provides evidence of quantum nonlocality. Experimental verification is required to confirm whether a quantum system of extremely large dimension can possess this feature, however it has never been performed for large dimension. Here, we report that Bell inequalities are experimentally violated for bipartite quantum systems of dimensionality d = 16 with the usual ensembles of polarization-entangled photon pairs. We also estimate that our entanglement source violates Bell inequalities for extremely high dimensionality of d > 4000. The designed scenario offers a possible new method to investigate the entanglement of multipartite systems of large dimensionality and their application in quantum information processing.
d维（d≥2）二分系统中空间分离部分之间的量子关联没有经典的对应物。这种关联，也称为纠缠，不仅在概念上很重要，而且对信息科学有深远影响。理论上，基于d维系统的局域实在论对贝尔不等式的违背提供了量子非局域性的证据。需要通过实验验证来确认维度极大的量子系统是否能具备这一特性，然而对于大维度情况从未进行过相关实验。在此，我们报告，利用通常的偏振纠缠光子对系综，对于维度d = 16的二分量子系统，贝尔不等式在实验中被违背。我们还估计，我们的纠缠源对于d>4000的极高维度违背贝尔不等式。所设计的方案为研究大维度多体系统的纠缠及其在量子信息处理中的应用提供了一种可能的新方法。
