中文摘要：

利用参量下转换和复合分束器相干叠加的方法制备了四比特超纠缠Greenberger-Horne-Zeilinger（GHZ）态，测量了纠缠体系的对比度和保真度。通过理论分析Ardehali不等式，得到了四比特纠缠体系的实验可测Ardehali算符。进而利用Ardehali算符在比特反转噪声环境中的期望值和噪声强度的关系，实验研究了四比特超纠缠体系的鲁棒性。结果表明，Ardehali不等式相对于定域实在论结果的违背随噪声强度的增加而下降。

英文摘要：

Using the methods of parametric down conversion and coherent superposition in composite beam splitter, four bits hyper-entangled Greenberger-Horne-Zeilinger states have been prepared. Con- trast and fidelity of the entangled system have also been measured. Through the theoretical analysis of Ardehali inequality,we obtain a measurable Ardehali operator of the four qubit system. Using the rela- tion between the expected value of Ardehali operator and the bit reversal noise intensity,the robustness of the four qubit system is investigated. The results show that the violation of Ardehali inequality versus local realism results decreases with the noise intensity increasing.