通过II型自发参量下转换制备纠缠光子对,在Mathematica环境下分析频率纠缠、频率关联、量子干涉特性及脉冲和晶体参数对特性的影响。结果表明,连续光抽运可以得到最大的频率纠缠度和干涉可见度;脉冲光频宽一定时,随着非线性晶体厚度的增大,双光子的联合光谱变窄,频率纠缠度增大,不可区分性减小,干涉可见度减小;非线性晶体厚度一定时,随着脉冲光频宽的减小,双光子的联合光谱变窄,频率纠缠度增大,不可区分性增大,干涉可见度增大;选取不同的联合光谱函数参数,可以得到具有频率反关联、不关联和正关联特性的双光子。

The type-II spontaneous parametric down conversion is used to prepare the entangled photon pairs. In the Mathematica environment, the properties of frequency entanglement, frequency correlation, quantum interference and the influences of parameters for pulse and crystal on the properties are analyzed. The results show that the continuous optical pumping can be used to obtain the maximum frequency entanglement and interference visibility. When the spectral width of pulsed laser is constant, as the nonlinear crystal thickness increases, the combined two-photon spectra become narrow, the frequency entanglement increases, the indistinguishability decreases, and the interference visibility decreases. In contrast, when the nonlinear crystal thickness is constant, as the spectral width of pulsed laser decreases, the combined two-photon spectra become narrow, the frequency entanglement increases, the indistinguishability increases, and the interference visibility increases. For different parameters of the combined spectral function, a photon pair with frequency anti-correlation, non-correlation and positive correlation can be obtained.