Fig. S3.

Impact of detuning on the spectral density and associated decay dynamics. Spectral density $g\left(\omega \right)$, normalized to its maximal value, and probability of occupation of the excited state, $P_e\left(t\right)$, for the configuration studied in Fig. 3 B and C of the main text ($r_2=5{\lambda }_p$), but artificially introducing a detuning between the transition dipole frequency ${\omega }_0$ and the resonance frequency ${\omega }_p$, such that $\mathrm{\Delta }\omega ={\omega }_p-{\omega }_0$, for (A) $\mathrm{\Delta }\omega =0.0001{\omega }_0$, (B) $\mathrm{\Delta }\omega =0.001{\omega }_0$, and (C) $\mathrm{\Delta }\omega =0.0025{\omega }_0$. The figure reveals that detuning does not result in a modulation of the vacuum Rabi frequency, but instead it weakens the reversible dynamics.