Fig. 2: Spin coherence and protection.

a, Rabi oscillations (purple circles) for a single hBN defect measured at high microwave power, fit to a function of the form exp(−t/T_Rabi)sin(2πtΩ − φ) (orange curve), where φ is the phase offset, Ω is the Rabi frequency and T_Rabi is the decay lifetime of the Rabi oscillations. The inset shows a zoomed-in view of the data. b, Q factor of the Rabi oscillations as a function of the Rabi frequency, where Q = T_Rabi/T_π and T_π = 1/2Ω. The presented data (purple circles) are calculated using T_Rabi and T_π extracted from fits to Rabi measurements using the equation above. The error bars are obtained from the 68% confidence intervals of each fit parameter. The Rabi measurement sequence is drawn above the panel (not drawn to scale), where r is the reference readout, s is the signal readout and t is the pulse duration. c, Ramsey measurements for different values of microwave frequency detuning Δ, from the resonance. The red curves are fit to exp(–\({t}{/}{{T}}_{{2}}^{{\,* }}{}\))sin(2πτΩ_Ramsey − φ). The diagram above the panel shows the microwave measurement sequence (not drawn to scale), where r is the reference readout, s is the signal readout and t is the pulse delay. All the measurements are measured in the absence of a magnetic field.