Functionals, excited-states and photonic environments of strongly coupled light-matter systems

Recent experiments at the interface of quantum optics and chemistry have realized altered materials properties using strong light-matter coupling. To describe this regime, electronic structure methods have been extended to capture strongly-coupled light-matter systems from first principles. In this talk, I give an overview on recent developments of the ab initio methods for strongly coupled light-matter systems, quantum-electrodynamical density-functional theory (QEDFT), cavity Born-Oppenheimer approximation (CBOA) and polaritonic coupled-cluster theory. This discussion includes the search for computationally efficient density functionals for QEDFT [1], pathways to improve their accuracy, as well as extensions of linear-reponse theories to include realistic electromagnetic environments via multi-mode setups and macroscopic QED.

[1] J. Flick, Phys. Rev. Lett. 129, 143201 (2022).