Photoexcitation and recombination processes of the neutral nitrogen-vacancy center in diamond from first principles

Nitrogen-vacancy (NV) complex in diamond is one of the most prominent solid state defects as the negatively charged NV defect (NV-) is a leading contender for quantum technologies. In quantum information processing applications, NV- is photoexcited that often leads to photoionization to neutral NV defect, NV0, and re-ionization back to NV- should occur to control the S=1 spin of NV-. As a consequence, understanding the photophysics of NV0 is crucial for controlling NV-. Furthermore, recent studies have shown that the S=1/2 electron spin of NV0 can also be initialized and read out at certain conditions that turns single NV0 a potential quantum bit. Quantum optics protocols rest on detailed knowledge on the electronic structure of the given system, which is obviously missing for NV0 in diamond. In this study, we combine the group theory and density functional theory calculations toward exploring the nature of the ground and excited states of NV0. We show that the effective three-electron system of NV0 leads to high correlation effects that make this system very challenging for ab initio simulations. (c) 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(https://creativecommons.org/licenses/by/4.0/).