Noise-Suppressed Quantum Sensing Using NV Pair Gradiometer

In the field of nanoscale sensing it is often necessary to detect very weak signals in the presence of large environmental background noise. To overcome this problem, differencing techniques are often used in an effort to cancel the background noise from distant sources. Here we investigate a magnetic gradiometer based on pairs on nitrogen vacancy (NV) color centers in diamond. By simulating NV pairs that are not resolved optically, it is shown that sensitivity to uniform magnetic fields can be strongly suppressed, while sensitivity to magnetic gradients remains good. The proposed scheme applies even if the NV pairs are not close enough to be entangled.