Fig. 3. Comparison of the subradiant and superradiant lifetimes.

a Decays curves of the subradiant and superradiant states. The laser pulses have a rise-fall time of 1 ns and a repetition rate 100 kHz. The solid curves are exponential fits with lifetimes τ₊ = 6.3 ns and τ₋ = 11.1 ns, which are consistent with the computed subradiant lifetime ${{\tau }_{-}=\left({\gamma }_0-2ab{\gamma }_{12}\right)}^{-1}={1.43\gamma }_0^{-1}$ and the superradiant one ${{\tau }_{+}=\left({\gamma }_0+2ab{\gamma }_{12}\right)}^{-1}={0.77\gamma }_0^{-1}$, using a = 0.88, b = 0.47, γ₁₂ = 0.35γ₀. The coefficients a and b are deduced from the diagonalization of the Hamiltonian H in the absence of laser field. The detuning Δ = 15γ₀ is derived from the splitting between |A〉 and |S〉 and from the coupling constant V = 9.5γ₀ that is deduced from the fits of the excitation spectra at various excitation intensities. Inset: Histogram of the lifetime of 35 uncoupled single molecules. The blue and red bars indicate the values of τ₊ and τ₋ for the coupled pair. b Evolution of τ₊ (blue circles) and τ₋ (red circles) with the molecular detuning Δ which is varied by differential Stark shifts of the molecular resonances from 15γ₀ to 32γ₀. The solid curves are the computed values of τ₊ and τ₋. The black circles are the inverse of the average subradiant and superradiant decay rates (${\tau }_{+}^{-1}$ and ${\tau }_{-}^{-1}$), and coincide with the average lifetime of the uncoupled single molecules (black dashed lines).