Covariance magnetometry using ensembles of diamond quantum sensors

Nitrogen vacancy (NV) centers in diamond enable nanoscale noise spectroscopy in condensed matter systems. In particular, NV centers can be used for 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. Additionally, we apply super-resolution techniques to access tunable, sub-diffraction-limit correlation length scales, and report on the application of this platform to study magnetic fluctuations and critical dynamics in condensed matter systems.