Temperature dependence of phonon-limited spin relaxation rates of nitrogen-vacancy centers*

Understanding the limits to the electronic spin coherence of the nitrogen-vacancy (NV) center in diamond is vital to realizing the full potential of this quantum system. In prior work, we found that at room temperature the double-quantum relaxation rate is approximately twice the single-quantum relaxation rate, limiting the maximum theoretically achievable coherence time for an NV under ambient conditions to 6.8(2) ms. We presented theoretical arguments showing that the two-phonon Raman process which is believed to provide major contributions to the single-quantum relaxation rate at 295 K is forbidden from driving double-quantum relaxation [1]. Here we present experimental measurements of the phonon-limited double-quantum relaxation rate of the NV as a function of temperature. In addition, we discuss our theoretical efforts towards understanding the observed temperature dependence of the double-quantum relaxation rate, which may shed new light on spin-phonon coupling in the NV and may inform strategies to mitigate this relaxation.

[1] M. C. Cambria, et al., State-dependent phonon-limited spin relaxation of nitrogen-vacancy centers, Phys. Rev. Research 3, 013123 (2021).