Experimental preparation and nonlocality of the high-pure four-photon Greenberger-Horne-Zeilinger states
HuaiXin LU, Lianzhen Cao, JiaQiang ZHAO, XiaoQin WANG · Zhongguo kexue. Wulixue Lixue Tianwenxue · 2013
Using the spontaneous parametric down conversion and post-selection method, we experimentally prepare the four-photon Greenberger-Horne-Zeilinger (GHZ) states with a high fidelity about 83.1%. Then, an efficiently method to improve the contrast ratio of the four-photon state is reported by theoretical analysis and experiment optimization. Based on the state, we study the local realism of this state and achieve 28 standard deviations, confirm the existence of genuine four-particle entanglement. Our work has important significance for experimental preparation and studying nonlocality of the high-fidelity multiple-photon entanglement states.