Fig. 5: Determination of the spin-cavity coupling constant for θ₂.

Evolution of the cavity quality factor Q_s with detuning Δ at selected temperatures for the transitions \({{{{\rm{T}}}}}_{3}^{{\theta }_{2}}\) (a) and \({{{{\rm{T}}}}}_{1}^{{\theta }_{2}}\) (b). Symbols correspond to data extracted from the Lorenztian fit of ∣S₂₁(ω)∣² and full lines to the fit to Eq. (7). Magnitude of S₂₁(ω) in color scale as a function of detuning across the two Electron Spin Resonance (ESR) transitions, \({{{{\rm{T}}}}}_{3}^{{\theta }_{2}}\) (c) and \({{{{\rm{T}}}}}_{3}^{{\theta }_{2}}\) (d). The light blue dashed lines represent the resonance frequency ω_r extracted from the simulations of Eq. (5) assuming the values of \(\bar{\Omega }\) and γ_s determined by the fit of Q_s, while the black dashed lines represent the vacuum Rabi frequencies ω_± defined in Eq. (6).