Molecule-photon interactions in phononic environments

TL;DR

This paper investigates the quantum dynamics of molecules interacting with phononic environments, identifying decoherence mechanisms and proposing ways to enhance vibrational coherence for quantum optical applications.

Contribution

It introduces an open quantum system approach to analyze vibrational relaxation regimes and predicts collective vibron dynamics, advancing understanding of phonon-induced decoherence in molecular systems.

Findings

Identification of Markovian and non-Markovian vibrational regimes

Prediction of collective vibron-vibron dynamics resembling superradiance

Proposal for decoupling intramolecular vibrations to extend coherence times

Abstract

Molecules constitute compact hybrid quantum optical systems that can interface photons, electronic degrees of freedom, localized mechanical vibrations and phonons. In particular, the strong vibronic interaction between electrons and nuclear motion in a molecule resembles the optomechanical radiation pressure Hamiltonian. While molecular vibrations are often in the ground state even at elevated temperatures, one still needs to get a handle on decoherence channels associated with phonons before an efficient quantum optical network based on opto-vibrational interactions in solid-state molecular systems could be realized. As a step towards a better understanding of decoherence in phononic environments, we take here an open quantum system approach to the non-equilibrium dynamics of guest molecules embedded in a crystal, identifying regimes of Markovian versus non-Markovian vibrational relaxation. A stochastic treatment based on quantum Langevin equations predicts collective vibron-vibron dynamics that resembles processes of sub- and superradiance for radiative transitions. This in turn leads to the possibility of decoupling intramolecular vibrations from the phononic bath, allowing for enhanced coherence times of collective vibrations. For molecular polaritonics in strongly confined geometries, we also show that the imprint of opto-vibrational couplings onto the emerging output field results in effective polariton cross-talk rates for finite bath occupancies.