We present here our results on using liquid crystals (LCs) in experiments with nonclassical light sources: (1) single-photon sources exhibiting antibunching (separation of all photons in time), which are key components for secure quantum communication systems and (2) entangled photon source with photons exhibiting quantum interference in a Hong–Ou–Mandel interferometer. In the first part, both nematic and cholesteric liquid crystal (CLC) hosts were used to create definite linear or circular polarization of antibunched photons emitted by different types of single emitters (dye molecules, nanocrystal quantum dots (NQDs), nanodiamonds with color centers, etc.). If the photon has unknown polarization, filtering it through a polarizer to produce the desired polarization for quantum key distribution with bits based on polarization states of photons will reduce by half the efficiency of a quantum cryptography system. In the first part, we also provide our results on observation of a circular polarized microcavity resonance in NQD fluorescence in a 1-D chiral photonic bandgap CLC microcavity. In the second part of this paper with indistinguishable, time-entangled photons, we demonstrate our experimental results on simulating quantum mechanical barrier tunneling phenomena. A Hong–Ou–Mandel dip (quantum interference effect) is shifted when a phase change was introduced on the way of one of entangled photons in pair (one arm of the interferometer) by inserting in this arm an electrically controlled planar-aligned nematic LC layer between two prisms in the conditions close to a frustrated total internal reflection. By applying different AC-voltages to the planar-aligned nematic layer and changing its refractive index, we can obtain various conditions for incident photon propagation – from total reflection to total transmission. Measuring changes of tunneling times of photon through this structure with femtosecond resolution permitted us to answer some unresolved questions in quantum mechanical barrier tunneling phenomena.

我们在此介绍在非经典光源的实验中使用液晶（LC）的结果：（1）单光子源表现出反聚束（所有光子在时间上分离），这是安全量子通信系统的关键组件；（2）在Hong-Ou-Mandel干涉仪中纠缠的光子源与表现出量子干涉的光子。在第一部分中，使用向列和胆甾型液晶（CLC）主机来产生确定的线性或圆极化不同类型的单个发射器（染料分子，纳米晶体量子点（NQD），具有色心的纳米金刚石等）发射的反聚束光子。如果光子具有未知的偏振，则通过偏振器对其进行过滤以产生所需的偏振，以根据基于光子的偏振态的位进行量子密钥分配，这将使量子密码系统的效率降低一半。在第一部分中，我们还提供了在一维手性光子带隙CLC微腔中NQD荧光中观察到圆偏振微腔共振的结果。在本文的第二部分中，使用不可区分的时间纠缠的光子，我们演示了模拟量子力学势垒隧穿现象的实验结果。当在成对纠缠的一个光子对中的一个（干涉仪的一个臂）的路径上引入相变时，通过在该臂中插入电控制的平面对准向列LC，可以改变Hong-Ou-Mandel倾角（量子干涉效应）在接近受挫的全内反射的条件下，两个棱镜之间的反射层。通过向平面排列的向列层施加不同的交流电压并更改其折射率，我们可以获得入射光子传播的各种条件-从全反射到全透射。通过飞秒分辨率测量光子通过该结构的隧穿时间的变化，使我们能够回答量子力学势垒隧穿现象中一些未解决的问题。