Coherent nonlinear optical probes for cavity-dressed vibrational mode mixing: Multidimensional double-quantum...

Cavity dressing of molecular vibrational dynamics expands the role of characteristic vibrations as spectroscopic markers of underlying ultrafast dynamics. Interacting vibrational modes exhibit pronounced excited state delocalization due to the interaction with the cavity mode, which is reflected in the ultrafast dynamics. We characterize the ultrafast dynamics of cavity-dressed characteristic vibrations, namely vibrational polaritons, in the presence of dissipation and collective vibrational nonlinearity. Specifically, we present two complementary three-pulse coherent multidimensional spectroscopic techniques for monitoring the dynamics of cavity-dressed one- and two-quantum vibrational excitations. A microscopic theory that includes low- and high-energy phonon modes consistently describes the dissipative dynamics, including population relaxation and dephasing. The cavity coupling strengths are comparable to the vibrational mode couplings, suggesting the possibility of controlling intermolecular vibrational energy redistribution. This simulation framework is extendable to various cases of cavity-controlled nonlinear spectroscopies of dissipative molecular systems, including large ensembles.