Controlled Surface Modification to Revive Shallow NV<sup>–</sup> Centers
Jeffrey Neethirajan, Toni Hache, Domenico Paone, Dinesh Pinto, Andrej Denisenko, Rainer Stöhr, Péter Udvarhelyi, Anton Pershin, Ádám Gali, Jörg Wrachtrup, Klaus Kern, Aparajita Singha
Abstract
High Resolution Image Download MS PowerPoint Slide Near-surface negatively charged nitrogen vacancy (NV) centers hold excellent promise for nanoscale magnetic imaging and quantum sensing. However, they often experience charge-state instabilities, leading to strongly reduced fluorescence and NV coherence time, which negatively impact magnetic imaging sensitivity. This occurs even more severely at 4 K and ultrahigh vacuum (UHV, p = 2 × 10 –10 mbar). We demonstrate that in situ adsorption of H 2 O on the diamond surface allows the partial recovery of the shallow NV sensors. Combining these with band-bending calculations, we conclude that controlled surface treatments are essential for implementing NV-based quantum sensing protocols under cryogenic UHV conditions.