Charge stability and charge-state-based spin readout of shallow nitrogen-vacancy centers in diamond

Rakshyakar Giri; Rasmus H. Jensen; Deepak Khurana; Juanita Bocquel; Ilya P. Radko; Johannes Lang; Christian Osterkamp; Fedor Jelezko; Kirstine Berg-Sorensen; Ulrik L. Andersen; Alexander Huck

arXiv · 2208.14154

Charge stability and charge-state-based spin readout of shallow nitrogen-vacancy centers in diamond

Rakshyakar Giri·Rasmus H. Jensen·Deepak Khurana·Juanita Bocquel·Ilya P. Radko·Johannes Lang·Christian Osterkamp·Fedor Jelezko·Kirstine Berg-Sorensen·Ulrik L. Andersen·Alexander Huck

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Abstract

Spin-based applications of the negatively charged nitrogen-vacancy (NV) center in diamonds require efficient spin readout. One approach is the spin-to-charge conversion (SCC), relying on mapping the spin states onto the neutral (NV$^0$) and negative (NV$^-$) charge states followed by a subsequent charge readout. With high charge-state stability, SCC enables extended measurement times, increasing precision and minimizing noise in the readout compared to the commonly used fluorescence detection. Nano-scale sensing applications, however, require shallow NV centers within a few $\si{\nano \meter}$ distance from the surface where surface related effects might degrade the NV charge state. In this article, we investigate the charge state initialization and stability of single NV centers implanted $\approx \SI{5}{\nano \meter}$ below the surface of a flat diamond plate. We demonstrate the SCC protocol on four shallow NV centers suitable for nano-scale sensing, obtaining a reduced readout noise of 5--6 times the spin-projection noise limit. We investigate the general applicability of SCC for shallow NV centers and observe a correlation between NV charge-state stability and readout noise. Coating the diamond with glycerol improves both charge initialization and stability. Our results reveal the influence of the surface-related charge environment on the NV charge properties and motivate further investigations to functionalize the diamond surface with glycerol or other materials for charge-state stabilization and efficient spin-state readout of shallow NV centers suitable for nano-scale sensing.

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Rakshyakar Giri, Rasmus H. Jensen, Deepak Khurana, Juanita Bocquel, Ilya P. Radko, Johannes Lang, Christian Osterkamp, Fedor Jelezko, Kirstine Berg-Sorensen, Ulrik L. Andersen, Alexander Huck. 2022-08-30. Charge stability and charge-state-based spin readout of shallow nitrogen-vacancy centers in diamond. https://arxiv.org/abs/2208.14154

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