Sensors using individual atomic defects in diamond have revolutionized local magnetic sensing. This technology is based on the insight that higher densities of defects can produce more sensitive detectors. However, at very high densities, interactions between defects complicate the detector operation. Specifically, when the spins in a quantum detector get too close, they typically hit an interaction-limited sensitivity threshold. This technology innovation considered the effect of a periodic external field that depends on the nature of the interactions. The discovery uses a periodic driving of the spin system to enable a sensor to surpass previous limits on using high densities of spins.

This fundamental innovation applies to spin ensembles in general. These are ubiquitous in solid matter, either due to spins of the atomic nuclei, or due to localized electron spins as in the case of nitrogen-vacancy defects in diamond. In particular, the technique could be used to sense the magnetic field at the surface of a dense, 2D array of nitrogen-vacancy defects. Alternatively, Carbon-13 nuclei doped into graphene could also be driven into the collective states that form the basis of the sensing strategy.

Applications of magnetic field sensing using nitrogen vacancy centers are broad, including quantum computing applications, molecular sensing for chemistry and pharmaceutical applications, cell biology, and more.

A preprint has been published here.