Abstract
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.
Highlights
Quantum defects in solids are emerging as the sensors of choice for detecting micrometer to nanometer phenomena in a wide range of systems in both the physical and life sciences
Current room temperature NV experiments rely on a spin-dependent fluorescence signal that is restricted to a short detection window (∼250 ns), after which the spin is optically pumped into the ms = 0 state, such that the spin-state-dependent fluorescence is typically limited to about a fraction of a photon per readout window for a single NV center [1]
A new NV spin readout technique based on spin-to-charge conversion (SCC) that overcomes this limitation was demonstrated in diamond nanobeams [12], in which the single NV fluorescence is enhanced by an order of magnitude compared to NV centers in bulk diamond
Summary
Quantum defects in solids are emerging as the sensors of choice for detecting micrometer to nanometer phenomena in a wide range of systems in both the physical and life sciences. Sensitivity is not the optimal figure of merit for many applications such as sensing on-demand pulsed fields In this case, the single shot precision – equivalent to the smallest signal that can be detected in a single measurement independent of the time it takes – is a better figure of merit. The single shot precision – equivalent to the smallest signal that can be detected in a single measurement independent of the time it takes – is a better figure of merit In this case, we again find that SCC readout outperforms conventional readout for single NV quantum sensing protocols like ”coherently averaged synchronized readout” (CASR) where the sequence is triggered by an external clock or coherent signal [14,15,16]. To overcome the limitations of finite NV spin lifetime while maintaining high spectral resolution sensing, the CASR protocol typically includes time fillers that can extend the duration of the NV readout and thereby make SCC especially advantageous
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