Comparison of coherence times extracted from Rabi oscillation (grey squares) and spin echo measurements (blue circles), as a function of Rabi frequency. For Rabi oscillations the coherence time decreases at high Rabi frequency due to fluctuations in drive strength 34 . For spin echo, the coherence time saturates at high Rabi frequencies, where the pulse is shorter relative to the spin precession time. The saturation value is close to that calculated by Haykal et al. (dashed-line) for hBN with natural isotope distribution 3 . The Rabi oscillations are fitted to f(\tau )=a+b{e}^{-\tau /{T}_{Rabi}}\cos ({\Omega }\tau ) , and spin echo to g(\delta )=-a.{e}^{-2\delta /{T}_{echo}} . The error bars indicate the standard error of the fit coherence times. Source data are provided as a Source Data file.
