with T = 1 ps, unless noted otherwise. Note that computations with larger values of T do lead to variations in the ⟨P iso ⟩ when compared to the T = 1 ps case (see Supplementary Fig. for the variation of ⟨P iso ⟩ with ω c for averaging time T = 2 ps). This is expected since the tunneling contribution can increase substantially over longer times for certain cavity frequencies. Moreover, from the rate computations reported , for low temperatures and η ∼ 0.06 (typical coupling strength value considered in this study) the timescale k -1 ∼ 0.7 ps. In any case, our computations indicate that the overall trends for different averaging times are qualitatively similar.