a, Energy of Rabi oscillations (g) vs mean number of MB molecules (n). Experimental (white) points with measured variance and theoretical curve (dashed), colours represent expectation from Poisson probability distribution of 'n'. b, Coupling strength extracted from different NPoMs in sample of 'n'=2.5. Theoretical coupling strength in perfect model (shaded bars) and random placement model (dashed lines). c-e, Scattering spectra for one, two and three molecules, with fits. f, Single-molecule probability histograms for 'n'=0.2 and 2.5 derived from modified principal component analysis analysis. Inset shows the signature of the two different probabilities.