Wavelet-enhanced Ramsey magnetometry of a nanodiamond single NV center*

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 a time-resolved spin-state-dependent photoluminescence (PL) data. Its sensitivity is ultimately limited by the photon shot noise (PSN), which cannot be sufficiently suppressed by averaging or frequency filtering. Here, we propose Ramsey magnetometry of a single NV center enhanced by a wavelet-denoising scheme tailored against PSN. Without invoking any quantum resource, it operates as a post-processing applied over a collected PL time series. Our implementation is based on template margin thresholding which we computationally benchmark, and demonstrate its signal to noise ratio improvement over the standard quantum limit of up to an order of magnitude for the case of limited resources.