Hybridization of molecules via a common photonic mode.

Atoms and molecules usually hybridize and form bonds when they come in very close proximity of each other. In this work, we show that molecules can hybridize even through far-field electromagnetic interactions mediated by the shared mode of an optical microcavity. We discuss a collective enhancement of the vacuum Rabi splitting and study super- and subradiant states that arise from the cavity-mediated coupling both in the resonant and dispersive regimes. Moreover, we demonstrate a two-photon transition that emerges between the ground and excited states of the new optical compound. Our experimental data are in excellent agreement with the predictions of the Tavis-Cummings Hamiltonian and open the door to the realization of hybrid light-matter materials.