Readout optimisation for spin-based quantum sensing using the nitrogen vacancy centre in diamond

Abstract Quantum sensors based on nitrogen vacancy (NV) defects in diamond have a demonstrated capability to detect nuclear magnetic resonance (NMR) spectra from proximate molecular nuclei, thereby promising an alternative with higher sensitivity to conventional NMR spectrometers for micro-scale samples. Fluorescence-based readout of these sensors is limited by higher shot noise due to the small number of emitters and photoionisation induced instabilities, meaning there is still significant scope to maximise their sensitivity and temporal resolution. In this work, we demonstrate a new readout protocol based on parameter fitting to a precise model of the NV photo-physics, thereby demonstrating an improvement of 36% in sensitivity and 85% gain in measurement speed. Whereas typical approaches to improvement involve expensive diamond material, and optical and microwave engineering, our method can be readily implemented into existing NV quantum sensing protocols.