Massively Multiplexed Covariance Magnetometry with 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 utilize parallel addressing and readout to enable massively multiplexed covariance magnetometry in two platforms: in the first, we leverage individually resolvable NV centers for multiplexed correlation measurements with nanoscale precision. In the second, we use ensembles of NV centers for high-sensitivity correlation measurements on micron-scales with access to higher-order joint cumulants. We apply both of these platforms to study the dynamical fluctuations of thin-film superconductors and layered antiferromagnetic materials, probing their critical properties and non-equilibrium behaviors.