光子两自由度超纠缠态制备、度量及其在量子通信中的应用研究

Photons are the ideal information carriers for quantum communication as they move fast, can be manipulated easily, be prepared cheaply, and interact weakly with environment. Hyperentanglement, defined as the quantum system entangled in two or more degrees of freedom (DOFs), can improve the channel capacity doubly in quantum communication and the power for quantum computation. It can reduce the quantum source consumed in quantum information processing and depress the influence from loss arisen from noise. Investigation on the preparation of hyperentanglement and its application is interesting and valuable. In this project, we will investigate deeply the preparation of hyperentanglement in two DOFs by using BBO crystals in experiment, measure it with quantum correlation and Bell inequality in two DOFs, and explore the efficient way for producing the photon systems in maximally hyperentangled states. Moreover, we will study the complete distinguishing of the 16 hyperentangled states with linear optical elements and time-bin DOF and its application in teleportation and hyperdense coding with the quantum states in two DOFs. We hope we will have some important contributions to quantum communication with hyperentangled states through this project.

光子传输速度快、易操控、制备成本低、受环境噪声影响弱，是量子通信中最理想的信息载体。光子系统在两个及以上自由度存在纠缠的量子态称为超纠缠态，它可以成倍提高量子通信的信道容量、提升量子计算并行计算能力、节约资源并减少损耗噪声的影响。因此研究光子系统超纠缠态制备及其在量子通信应用，具有很好的科学意义与应用价值。本项目主要研究光子两自由度超纠缠态的实验室制备、度量及其在量子通信中的应用，具体内容包括：利用非线性BBO晶体制备两光子两自由度超纠缠态，利用量子关联和两自由度类Bell不等式对超纠缠态进行度量，并探索高效率制备高纯度超纠缠态光子系统方法；利用时间等自由度和线性光学元件，区分极化与空间两自由度超纠缠态，并应用于两自由度量子态隐形传输、超密集编码等基本的量子通信任务。通过本项目研究，寻找低成本高效率制备两自由度超纠缠态光子系统的方法和线性光学区分方法，为超纠缠态在量子通信中的应用做出贡献。

光子系统在两个及以上自由度存在纠缠的量子态称为超纠缠态，它可以成倍提高量子通信的信道容量、提升量子计算并行计算能力、节约资源并减少损耗噪声的影响。因此研究光子系统超纠缠态制备及其在量子通信应用，具有很好的科学意义与应用价值。本项目主要研究光子两自由度超纠缠态的实验室制备、度量及其在空间多维信息传输中的应用，具体内容包括：利用非线性参量过程制备双光子多自由度纠缠态，并实现多维信息传输；结果证明：利用多自由度超纠缠态可以实现获得接近1 / 4的单光子传输的成功概率；另外，多自由度超纠缠态的使用可以有效降低利用诱骗光子检测的传输安全性的影响及环境噪声的退相干，从而实现以前的高容量量子直接通讯协议更高的信息容量；开展了利用多维关联技术实现多维度光学信息传输实验。实现多维空间关联信息的加密与提取、可见水印技术与不可见水印编码、基于量子关联技术实现多重散射噪声环境高质量的多维信息的传输。