Wide-field covariance magnetometry using ensembles of diamond quantum sensors

Nitrogen vacancy (NV) centers in diamond enable high-sensitivity magnetometry of condensed matter systems with nanoscale resolution, but conventional measurements report on averaged local magnetic fields, limiting understanding of non-local dynamics. Our group recently developed a new technique, covariance magnetometry, which leverages multiple quantum sensors to measure temporal dynamics of the magnetic field at many positions simultaneously, from which the local noise spectrum and non-local properties such as correlation functions can be computed. In this work, we develop a multiplexed covariance magnetometry platform using ensembles of NV centers. By spatially averaging the signal from many NV centers, we perform high-sensitivity and high-throughput correlation measurements on micron-scales with wide-field imaging, allowing access to unique measurements such as higher-order joint cumulants and vector magnetic field correlators. Additionally, we apply super-resolution techniques to increase the spatial resolution of ensemble correlation measurements, and report on the application of this platform to study magnetic fluctuations and critical dynamics in condensed matter systems.