金刚石NV色心量子纠缠的实验研究

The kennel tasks of quantum information science are the production, control and detection of quantum states. After more than ten years' investigation and development, the combination of single solid state quantum system and optics has been one of the most important candidates and basic units for the realization of quantum information techniques. Especially, Nitrogen-Vacancy (NV) centers in diamond have been paid more and more attention because of their excellent optical and electrical properties. This project will study quantum information techniques with coupling NV centers in diamond systematically. The project will solve the artificial fabrication of NV centers. Micro-optical structures will be fabricated to enhance the emission rate of NV center and the coupling efficiency of emitted photons from NV center. Therefore, the efficiency of the quantum state detection can be increased. Also, the control of the coupling NV centers will be studied. The coupling strength can be controled by magnetic field, while the readout and control of quantum states can be realized by the quantum statistical measurement method. The project will also aim at the realiztion of the entanglement between two NV centers and two-qubit quantum gate for quantum information techniques. With the projet, we will realize essential quantum information manipulation with diamond NV centers and achieve basic units and kernel techniques for quantum information processes. It will be good technical accumulation for future quantum network and integrated quantum chip.

量子信息科学研究的核心是量子态的产生，控制及探测。经过十多年的研究和发展，基于固态单量子体系与光学耦合系统是构建量子信息技术的一种主要候选手段和基本单元，尤其是金刚石材料中的氮-真空缺陷（NV）色心因为其优越的光学和电子态性质越来越受关注。本项目将系统地研究耦合金刚石NV 色心系统在量子信息技术方面的应用。项目将解决和完善金刚石NV色心的人工制备。通过微纳光学技术提高NV色心荧光发射强度和收集效率，并实现NV色心量子态的高效探测。研究耦合NV色心量子态的控制，利用外加磁场调节NV色心间的耦合强度，利用量子统计测量技术实现耦合NV色心纠缠的读出和操控。项目的研究目标是实现耦合NV色心纠缠态并实现两比特量子门操作以及其他量子信息处理。通过本项目，进一步实现基于金刚石NV色心体系的量子信息处理基本元件，掌握其在量子信息操作中的核心技术，并将在未来量子网络和集成化量子芯片中得到应用。

金刚石氮-空位(NV)色心因为其在室温下的长相干时间、高光学稳定性等特性已经成为实现量子信息技术一种重要的物理体系。本项目开展了金刚石样品和NV色心的人工制备，微纳光学结构与NV色心的耦合，NV色心电子自旋态操控以及在量子计算、量子精密测量的中的应用。项目实现了单晶金刚石样品制备，以及相干时间长达7微秒的单个NV色心和耦合强度达4.9KHz邻近NV色心的人工制备和测量。实现了利用纳米锥结构和金属表面等离子体将NV色心单光子计数分别提高了6倍和2.6倍。实现了超低功率电荷态耗尽纳米成像术，分辨率达4.1纳米。基于该纳米成像术，实现两个近邻NV 色心量子态的识别和独立控制，实现了高空间分辨率磁场矢量的测量。基于电子自旋-核自旋纠缠体系实现了高保真度的量子Deutsch–Jozsa算法，保真度达97%。此外，理论上提出了基于连续模式中束缚态理论的新型光学波导和微腔结构提高光子与NV电子自旋的相互作用强度。理论提出金刚石NV色心电子纠缠态制备，并提出了应用于多比特量子精密测量的抗噪声方案，使得在真实消相干环境下的量子精密测量的精度恢复到N^(-11/12)。该项目的完成为利用金刚石NV色心体系实现实用化的量子信息操作打下了坚实基础和积累了关键实验技术。