Quantum-Electrodynamical Time-Dependent Density Functional Theory Description of Molecules Interacting with Light

TL;DR

This paper introduces a real-time quantum electrodynamical density functional theory approach to study how molecules interact via light, especially within optical cavities, revealing how shared electromagnetic fields induce coherence between distant molecules.

Contribution

It develops a novel computational method combining QED and TDDFT to simulate light-molecule interactions, highlighting cavity-induced coherence effects.

Findings

In free space, excitation remains localized with no distant response.

Within a cavity, excitation induces coherent dynamics in distant molecules.

Shared cavity modes enable long-range light-mediated molecular interactions.

Abstract

We study light-mediated interactions between spatially separated molecules using real-time quantum electrodynamical time-dependent density functional theory based on the Pauli-Fierz Hamiltonian. An ultrashort delta-kick excitation selectively perturbs a single molecule, while a second, distant molecule remains initially unexcited. In free space, the excitation stays localized and no response is observed in the second molecule. In contrast, when both molecules are coupled to the same cavity mode, the initial excitation induces coherent dynamics in the distant molecule through the shared quantized electromagnetic field.