Bright $\mathrm{\textit{ab-initio}}$ photoluminescence of NV+ in diamond

TL;DR

This study uses ab initio calculations to reveal that the NV+ center in diamond can emit light at 765 nm, challenging the view of it as a dark state and opening new avenues for quantum applications.

Contribution

First ab initio prediction of photoluminescence in NV+ centers, showing their potential as quantum emitters with specific optical signatures.

Findings

NV+ exhibits quantum emission at 765 nm

Transition dipole moment is about 4 times smaller than NV-

Charge quenching mechanisms may explain experimental darkness

Abstract

The positively charged nitrogen vacancy (NV+) centre in diamond has been traditionally treated as a dark state due to the experimental lack of an optical signature. Recent computational studies have shown that it is possible for the NV+ defect to have an excited state transition equivalent to that of the negatively charged (NV-) centre, but no PL predictions have been reported so far. We report the first $\mathrm{\textit{ab-initio}}$ calculation showing that the NV+ center presents quantum emission, with zero phonon line at 765 nm and a non-zero transition dipole moment, approximately 4x smaller than the transition dipole moment of NV-. We calculate the energy levels of the multielectron states under time-dependent density functional theory (singlet and triplet E states), and using our recently developed frequency cutoff method, we predict the full PL spectrum. Our results suggest that this state cannot be considered intrinsically 'dark' and charge specific quenching mechanisms should be investigated as the cause of the lack of optical activity in experimental characterizations.