Nanoscale covariance magnetometry with diamond quantum sensors

Nitrogen vacancy (NV) centers in diamond are atom-scale defects that can be used to sense magnetic fields with high sensitivity and spatial resolution. Typically, the magnetic field is measured by averaging sequential measurements of single NV centers, or by spatial averaging over ensembles of many NV centers, providing mean values containing no nonlocal information about the relationship between two points separated in space or time. Here we propose and implement a sensing modality whereby two or more NV centers are measured simultaneously, and we extract temporal and spatial correlations in their signals that would otherwise be inaccessible. We demonstrate measurements of correlated applied noise using spin-to-charge readout of two NV centers, and implement a spectral reconstruction protocol for disentangling local and nonlocal noise sources.

金刚石中的氮空位（Nitrogen vacancy, NV）中心是一类原子级缺陷，可用于实现高灵敏度、高空间分辨率的磁场传感。传统磁场测量通常通过对单个NV中心的连续测量结果取平均，或是对大量NV中心组成的整体进行空间平均来完成，最终得到的均值无法反映空间或时间上分离的两个点之间的非局域关联信息。本研究提出并实现了一种全新的传感模式：同时对两个或多个NV中心进行测量，并从中提取原本无法获取的信号时空关联特性。我们通过对两个NV中心开展自旋-电荷读出实验，实现了关联外加噪声的测量，并搭建了光谱重构协议以区分局域与非局域噪声源。