Using the entangled two-photon systems, we experimentally demonstrate the predictions of the analog Clauser-Horne- Shimony-Holt (CHSH) inequality and investigate the robustness of the CHSH-class inequality in the bit-flip noisy environment. We obtain the experimental results of CHSH inequality and analog CHSH inequality as SCHSH=2.64±0.02 and SanalogCHSH=2.76±0.02, respectively, and prove that the analog CHSH inequality is more robust against bit-flip noise than the CHSH inequality. It provides better advantages for the experimental study and application.

In this paper, by using the second-order parametric down-conversion of the nonlinear crystal, the spin-1 state is simulated by the two-photon polarization entangled modes. Through adjusting the laser pulse power density, the efficiency of second-order parametric down-conversion is enhanced. The intensity of the spin-1 state is 0.5/s. The fidelity of the state is up to F=0.891±0.002, and the contrast is C=17.3. The results provide a new method for Stern-Gerlach measurement on the spin-1 system.

Using two-step growth method and buffer layer annealing treatment, the double heterojunction structures of In_0.82Ga_0.18epilayer capped with InAs_0.6P_0.4layer were prepared on InP substrate by low pressure metal organic chemical vapor deposition (LP-MOCVD). Based on the high quality In_0.82Ga_0.18As structures, the In_0.82Ga_0.18PIN photodetector with cut-off wavelength of 2.56 μm at room temperature was fabricated by planar semiconductor technology, and the device performance was investigated in detail. The typical dark current at the reverse bias VR=10 mV and the resistance area product R₀A are 5.02 μA and 0.29 Ω·cm²at 296 K and 5.98 nA and 405.2 Ω·cm²at 116 K, respectively. The calculated peak detectivities of the In_0.82Ga_0.18As photodetector are 1.21×10¹⁰cm·Hz^1/2/W at 296 K and 4.39×10¹¹cm·Hz^1/2/W at 116 K respectively, where the quantum efficiency η=0.7 at peak wavelength is supposed. The results show that the detection performance of In_0.82Ga_0.18As prepared by two-step growth method can be improved greatly.

Using spontaneous parametric down conversion, polarization post selection and coincidence counting technique, the polarization Einstein-Podolsky-Rosen (EPR) entangled states are prepared. Experimental studies on the efficiency, contrast and fidelity with different pump laser intensities are performed systematically. The results show that the pump laser intensity distinctly influences the quality of entangled photons, especially the contrast and the fidelity. On the other hand, the pump efficiency of entangled photons is almost invariable, namely the entangled source brightness increases linearly with the increase of pump laser power.

利用制备的三光子偏振广义Greenberger-Horne-Zeilinger纠缠态，测量了三体纠缠度、Svetlichny不等式和广义Greenberger-Horne-Zeilinger态的密度矩阵.根据密度矩阵计算了三体纠缠度，测量得到了广义Greenberger-Horne-Zeilinger纠缠态的纠缠和非定域性之间的关系.结果表明：在实验误差范围内，三体纠缠度的实验测量值和理论值一致；Svetlichny算符的期望值和理论计算结果具有较好的一致性；体系非定域特性和体系的纠缠程度密切相关，当纠缠度减小时，非定域性减弱.

利用数值计算的方法,研究了Kerr介质腔中的J-C模型二能级原子和单模光场作用过程中信 息熵和纠缠演化,得到了Kerr效应对纠缠态纠缠性质的影响。结果表明,Kerr介质对耦合体系的纠缠 度有强烈的影响,在合适的Kerr效应下,量子态将长时间保持最大纠缠。

计算了三体W态的Svetlichny不等式,给出了W态非定域性的解析表达式, 讨论了W态的剩余纠缠。结果表明三体W态有着独特的共生纠缠和非定域特性,为进一步研究W态各量子比特 之间的纠缠特性以及纠缠动力学提供了理论依据。