Interaction-Enhanced Correlation Sensing via Non-Equilibrium Quench Dynamics

Nitrogen-vacancy (NV) centers are emerging as promising sensors for probing spatial correlations in fluctuating random fields. Experimental demonstrations of covariance magnetometry have relied on cross-correlating joint measurements of individually resolved sensors, which limits the accessible length scales and has an unfavorable quadratic dependence on readout noise. A key challenge in covariance magnetometry is to resolve tunable sub-diffraction length scales and improve signal-to-noise ratio.

We propose a class of many-body protocols that overcome these challenges, suitable for application on high-density, positionally-disordered ensembles of nitrogen-vacancy (NV) centers in diamond with strong dipolar interactions. Our approach exploits entanglement generated by quench dynamics, as well as strong magnetic field gradients, as a powerful tool for interaction-enhanced correlation spectroscopy with global readout. Target correlations are encoded onto the decay of the global magnetization signal, through momentum-space filter functions set by the specific dynamical protocol, generalizing the case of conventional Ramsey noise spectroscopy. Furthermore, the many-body setting provides the ability to probe the correlation function of the external signal at continuously tunable length scales ranging from NV-NV spacing (~10 nm) to several um, potentially enabling distinguishing phases of target quantum materials from the functional form of their structure factors.