Preparation of generalized Greenberger-Horne-Zeilinger and measurement of nonlocality
HuaiXin LU, JiaQiang ZHAO, XaoQin WANG · Zhongguo kexue. Wulixue Lixue Tianwenxue · 2011
Using spontaneous parametric down conversion and optimizing the scheme of experiment, we prepared the generalized Greenberger-Horne-Zeilinger (GGHZ) states. With over-complement quantum tomography, we achieve the density matrix and calculate the fidelity of the state as 85%±1%. Then, based on the state, we measure the expectation value of Bell-Mermin operator. In the experiment we obtained accordant result with theoretical calculation. It is show that the nonlocality of quantum states is directly related to the degree of tripartite entanglement. And the results also testify our scheme of GGHZ states and measure method of nonlocality.