title: Atoms and molecules in cavities, from weak to strong coupling in quantum-electrodynamics (QED) chemistry.
abstract: In this work, we provide an overview of how well-established concepts in the fields of quantum chemistry and material sciences have to be adapted when the quantum nature of light becomes important in correlated matter-photon problems. We analyze model systems in optical cavities, where the matter-photon interaction is considered from the weak- to the strong-coupling limit and for individual photon modes as well as for the multimode case. We identify fundamental changes in Born-Oppenheimer surfaces, spectroscopic quantities, conical intersections, and efficiency for quantum control. We conclude by applying our recently developed quantum-electrodynamical density-functional theory to spontaneous emission and show how a straightforward approximation accurately describes the correlated electron-photon dynamics. This work paves the way to describe matter-photon interactions from first principles and addresses the emergence of new states of matter in chemistry and material science.
authors.affiliation: Department of Physics, Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, 22761 Hamburg, Germany; angel.rubio@mpsd.mpg.de johannes.flick@mpsd.mpg.de.
authors.forename: Johannes
authors.initials: J
authors.lastname: Flick
authors.affiliation: Department of Physics, Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, 22761 Hamburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Ruggenthaler
authors.affiliation: Department of Physics, Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, 22761 Hamburg, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Appel
authors.affiliation: Department of Physics, Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science, 22761 Hamburg, Germany; angel.rubio@mpsd.mpg.de johannes.flick@mpsd.mpg.de.|Nano-Bio Spectroscopy Group and European Theoretical Spectroscopy Facility (ETSF), Departamento de Fisica de Materiales, Universidad del País Vasco, 20018 San Sebastián, Spain.
authors.forename: Angel
authors.identifier: 0000-0003-2060-3151
authors.initials: A
authors.lastname: Rubio
keywords: QED chemistry; adiabatic polariton surfaces; local control; optimized effective potential; quantum electrodynamical density functional theory