基于单原子与低维度系统非互易相互作用的量子调控及应用

Photonic system is a promising candidate for quantum information processing. It usually needs several quantum devices with different functions to constitute an optical quantum internet and to perform various quantum information processing tasks. The single-photon quantum router and the nondestructive photon sorter are of great importance due to their respective functions for controlling photon transmission and sorting photon state. Intensive attention has been drawn towards developing these quantum devices recently. This project aims to develop two single-photon routers controlled by a single photon and a high-efficiency nondestructive photon sorter. We will start this project by calculating several two-photon scattering processes when these photons are scattered by a single atom non-reciprocally coupled to different low-dimensional systems. Then, we will focus our research on the following topics: (1) A single-photon quantum router with two outputs controlled by a single photon will be researched by a ladder-type atom non-reciprocally coupled to a waveguide. A control photon impinged simultaneously along with a target photon into this router can direct the target photon into either output; (2) A single-photon quantum router with multiple outputs controlled by a single photon will be constructed by a chiral system consisting of a ladder-type atom, a ring cavity and two waveguides. This will be a multifunctional quantum router, which performs multiple control on the target photon by several photons; (3) A nondestructive photon sorter for distinguishing different Fock states will be researched. It enables not only the distinct discrimination between single-photon and two-photon states, but also the discrimination between two-photon and three-photon states. We hope that some interesting outcomes on quantum control and quantum-device construction can be obtained for the development of a practical quantum internet.

光子是量子信息处理的一种有效载体。在光量子网络和光量子信息处理过程中，往往需要协调操控多种不同功能的量子器件。单光子量子路由和非破坏性光子分类器是两类非常重要的量子器件，分别用于光子传输方向调控和光子态分类，是当前量子信息的研究热点。本项目旨在研究无经典驱动场的同步单光子量子路由和高分辨率的非破坏性光子分类器。在系统性地探讨了单原子与几类低维度系统非互易相互作用下的双光子散射过程之后，按如下三个主要内容开展：（1）研究两输出端口同步单光子量子路由，实现单光子同步调控另一个光子在两输出端口的输出分布；（2）探讨多输出端口同步单光子量子路由，构造具有多重功能、多重调控机制的量子器件；（3）研究光子数态表象下的非破坏性光子分类器，在分离单光子态和非单光子态的基础上，建立分离双光子态和三光子态的方法。本项研究力争在量子调控和量子器件方面取得一些原创性成果，推进其在量子网络中的应用。

单光子与静态量子比特的有效作用是实现高性能量子网络的一个核心，可以用于对光量子态的控制、测量以及存储等。本项目基于固态人工原子与低维系统耦合给出了极化单光子与固态单量子比特（电子自旋）准确定性耦合，利用后选择主动消除非理想散射过程引入的错误。提出了极化光子数宇称非破坏性测量方法，并用于多光子纠缠态的分析和多自旋比特纠缠态制备；结合光子时域模式的高维特性，提出并行的非局域量子纠缠制备方案，可通过单次传输单光子同时建立多对非局域电子自旋之间的纠缠，进而大幅降低光子传输随距离指数衰减的影响；提出基于真空诱导的单声子阻塞效应，可以应用于表面声波单声子的制备；发现基于非线性耗散的非互易奇异点和光场的非互易传输；最后，我们研究了测量设备缺陷下的量子网络通信等等。