Improved quantum sensing with a single solid-state spin via spin-to-charge conversion

Efficient optical readout of a single, solid-state electronic spin at room temperature is a key challenge for nanoscale quantum sensing. Here we apply the technique of spin-to-charge conversion to enhance the optical spin-state readout of a single Nitrogen-Vacancy (NV) color center in room temperature diamond, with no degradation in the NV spin coherence time. We demonstrate an order-of-magnitude improvement in spin readout noise per shot and about a factor of five improvement in AC magnetometry sensitivity, compared to the conventional NV spin-state optical readout method. This improvement is realized in a widely-applicable bulk diamond system. We show that selecting for successful charge state initialization leads to possible further improvement in sensitivity. This technique is well suited to sensing applications involving low duty cycle pulsed signals, e.g., in biomagnetometry, where long deadtimes demand optimized sensitivity per shot.