We report direct measurement of population dynamics in the excited state manifold of a nitrogen-vacancy (NV) center in diamond. We quantify the phonon-induced mixing rate and demonstrate that it can be completely suppressed at low temperatures. Further, we measure the intersystem crossing (ISC) rate for different excited states and develop a theoretical model that unifies the phonon-induced mixing and ISC mechanisms. We find that our model is in excellent agreement with experiment and that it can be used to predict unknown elements of the NV center's electronic structure. We discuss the model's implications for enhancing the NV center's performance as a room-temperature sensor.
@article{arxiv.1406.4065,
title = {Phonon-Induced Population Dynamics and Intersystem Crossing in Nitrogen-Vacancy Centers},
author = {M. L. Goldman and A. Sipahigil and M. W. Doherty and N. Y. Yao and S. D. Bennett and M. Markham and D. J. Twitchen and N. B. Manson and A. Kubanek and M. D. Lukin},
journal= {arXiv preprint arXiv:1406.4065},
year = {2015}
}