Disentangling collective coupling in vibrational polaritons with double quantum coherence spectroscopy

TL;DR

This paper uses double quantum coherence spectroscopy simulations to analyze the complex many-body structure of vibrational polaritons, revealing their hybrid light-matter nature and anharmonicities, advancing understanding of molecular-cavity interactions.

Contribution

It introduces a comprehensive simulation approach combining cavity Born-Oppenheimer Hartree-Fock and quantum dynamics to study vibrational polaritons beyond simplified models.

Findings

Double quantum coherence resolves hybrid polariton excitations.

Simulations reveal anharmonicities in polariton states.

Electronic structure response influences spectral features.

Abstract

Vibrational polaritons are formed by strong coupling of molecular vibrations and photon modes in an optical cavity. Experiments have demonstrated that vibrational strong coupling can change molecular properties and even affect chemical reactivity. However, the interactions in a molecular ensemble are complex, and the exact mechanisms that lead to modifications are not fully understood yet. We simulate two-dimensional infrared spectra of molecular vibrational polaritons based on the double quantum coherence technique to gain further insight into the complex many-body structure of these hybrid light-matter states. Double quantum coherence uniquely resolves the excitation of hybrid light-matter polaritons and allows to directly probe the anharmonicities of the resulting states. By combining the cavity Born-Oppenheimer Hartree-Fock ansatz with a full quantum dynamics simulation of the corresponding eigenstates, we go beyond simplified model systems. This allows us to study the influence of self-polarization and the response of the electronic structure to the cavity interaction on the spectral features even beyond the single-molecule case.