Quantum sensing with diamond defects at extreme conditions

在过去的二十年中，金刚石中的氮空位（NV）中心已被用于演示和开发各种静态磁场和电场，压力，温度，波动场等的传感协议。然而，还变得明显的是，这样的设备遭受某些缺点，特别是对于在非常高的磁场（>1特斯拉）和高应力（> 100 GPa）下的感测。使用金刚石中的IV族空位中心，特别是SiV、GeV和SnV络合物，可以克服这些缺点。该项目的目标是开发基于金刚石的量子传感器，用于在高磁场和高应力下进行传感，通常可以称为“极端条件下的传感”。该项目的核心是制造具有上级光学和自旋相干特性的浅IV族空位中心。初步估计表明，根据确切的实验条件，与适当的缺陷工程，相干时间可以增加两个数量级超出目前可实现的。工程方面的进展将得到理论工作的支持，这些理论工作将为IV族空位复合物的光学和自旋相干时间的基本极限提供指导和见解。然后，这些中心将用于展示两种超越基于NV中心的技术限制的概念验证传感协议：（i）Tesla范围磁场下的量子磁力测量;（ii）应力>100 GPa下的量子传感。对于后者，我们的目标是测量磁场，以及整个应力张量及其在“极端”压力下在金刚石晶体中的分布。沿着这些协议的实验演示，该项目的工作将产生关于极端条件下点缺陷基本性质的新知识，扩展金刚石作为量子材料的一般知识。缺陷物理学的基本方面将通过理论和实验之间的密切合作进行调查。

Over the past two decades the nitrogen-vacancy (NV) center in diamond has been used to demonstrate and develop a variety of sensing protocols for static magnetic and electric fields, pressure, temperature, fluctuating fields, etc. Large corporations and start-ups are currently bringing NV sensors to the next technology-readiness level. However, it has also become apparent that such devices suffer from certain shortcomings, in particular for sensing at very high magnetic fields (>1 Tesla) and high stresses (> 100 GPa). These drawbacks could be overcome using group-IV-vacancy centers in diamond, in particular SiV, GeV, and SnV complexes. The goal of the project is the development of diamond-based quantum sensors for sensing at high magnetic fields and high stresses, which can be generally called “sensing at extreme conditions”. At the core of the project is the fabrication of shallow group-IV-vacancy centers with superior optical and spin coherence properties. Preliminary estimates demonstrate that, depending on exact experimental conditions, with appropriate defect engineering, coherence times could be increased by two orders of magnitude beyond what is currently achievable. Advances in engineering will be supported by theoretical work that will provide guidance and insights into the fundamental limits of optical and spin coherence times of group-IV-vacancy complexes. These centers will then be used to demonstrate two proof-of-concept sensing protocols beyond the limitations of NV-center-based technologies: (i) quantum magnetometry at Tesla-range magnetic fields; (ii) quantum sensing at stresses >100 GPa. For the latter, we aim at the measurement of the magnetic field, as well as the entire stress tensor and its distribution in the diamond crystal at “extreme” pressures. Along with the experimental demonstrations of these protocols, the work in the project will yield new knowledge about fundamental properties of point defects in extreme conditions, expanding the general knowledge of diamond as a quantum material. Fundamental aspects of defect physics will be investigated via a very close collaboration between theory and experiment.