Wavelet-based Ramsey magnetometry enhancement of a single NV center in diamond

Nitrogen-vacancy (NV) centers in diamond constitute a solid-state nanosensing paradigm. Specifically for high-precision magnetometry, the so-called Ramsey interferometry is the prevalent choice where the sensing signal is extracted from time-resolved spin-state-dependent photoluminescence (PL) data. Its sensitivity is ultimately limited by the photon shot noise, which cannot be sufficiently removed by averaging or frequency filtering. Here, we propose Ramsey DC magnetometry of a single NV center enhanced by a wavelet-denoising scheme specifically tailored to suppress photon shot noise. It simply operates as a classical post-processing applied on a collected PL time series. Our implementation is based on a method that we named template margin thresholding which enables not only frequency but also time-dependent denoising. We computationally benchmark its DC magnetic field sensing signal-to-noise-ratio improvement over the raw PL data around an order of magnitude.