is the vibrational state of the N-th molecule with v þ þ v À þ v D in the product electronic state. The calculation in Eq. ( ) (see Supplementary Note 3 for a derivation) is reminiscent to the contemporary problem of boson sampling . Using the notation Up until now, we have shown that the rate coefficient depends on the number of molecules that take part in the VSC, which changes as the reaction progresses. To illustrate the cumulative effect on the kinetics, we numerically integrate the rate law