An improved spin readout for nitrogen vacancy center ensemble based on a maximum likelihood estimation method

Abstract

In this work, a spin readout method using fluorescence dynamics is proposed based on maximum likelihood estimation (MLE) for improving the pulsed spin readout accuracy of nitrogen vacancy (NV) center. This estimation method can saturate the Cramér–Rao bound and enhance the photon-shot-noise-limited spin readout accuracy by 20% compared with conventional photon summation method. By employing a rate equation model of the NV center, the exact solution for the fluorescence dynamics is obtained. Additionally, according to the rate equation model’s relationship with fluorescence dynamics, spin, and pumping light power, a practical MLE readout scheme is furnished, which is able to distinguish spin readout information and classical noise. Compared with the conventional method, the classical noise suppression capability can be improved by 300 times. It is anticipated that the MLE method will effectively benefit sensing capability based on the NV centers even other scalable defect complexes in solid systems.