M. C. Cambria, A. Gardill, Y. Li, A. Norambuena, J. R. Maze and S. Kolkowitz, “State-dependent phonon-limited spin relaxation of nitrogen-vacancy centers”, PHYSICAL REVIEW RESEARCH 3, 013123 (2021), https://doi.org/10.1103/PhysRevResearch.3.013123
Understanding the limits to the spin coherence of the nitrogen-vacancy (NV) center in diamond is vital to realizing the full potential of this quantum system. We show that relaxation on the |ms=−1⟩↔|ms=+1⟩ transition occurs approximately twice as fast as relaxation on the |ms=0⟩↔|ms=±1⟩ transitions under ambient conditions in native NVs in high-purity bulk diamond. The rates we observe are independent of NV concentration over four orders of magnitude, indicating they are limited by spin-phonon interactions. We find that the maximum theoretically achievable coherence time for an NV at 295 K is limited to 6.8(2) ms. Finally, we present a theoretical analysis of our results that suggests Orbach-like relaxation from quasilocalized phonons or contributions due to higher-order terms in the spin-phonon Hamiltonian are the dominant mechanism behind |ms=−1⟩↔|ms=+1⟩ relaxation, motivating future measurements of the temperature dependence of this relaxation rate.