Physics and Engineering Physics Colloquium

Johannes Flick, Ph.D., assistant professor, Department of Physics, City College of New York, will present, “First-Principle Approaches to Strong Light-Matter Coupling in Molecular and Extended Systems.”

In recent years, research at the interface of material science, chemistry, and quantum optics has surged and now offers new possibilities to study light-matter interactions. The combination of theoretical concepts from these fields presents an opportunity to create a predictive theoretical and computational approach from first principles that describes the correlated dynamics of electrons, nuclei, and the electromagnetic field on the same quantized footing.

In this talk, Flick will discuss how density-functional theory can be generalized to quantum-electrodynamical density-functional theory (QEDFT) and show how new exchange-correlation potentials arise. We discuss the linear-response theory for QEDFT to access excited state properties of such systems, the emerging ab initio lifetimes, and the incorporation of losses. By considering electrons, nuclei, and photons on the same quantized footing, we find polaritonically induced vibrational mode mixing, cavity-modulated molecular motion of molecules in optical cavities, as well as new light-matter correlated observables for a new type of spectroscopy. Further, we use this novel framework to study how chemical reactivity is altered in this regime, by studying the modification of potential-energy surfaces under strong light-matter coupling. Beyond molecular systems, we will discuss how strong light-matter coupling can be used to make nonlinear phonon processes more efficient and discuss first principle methods to characterize novel single-photon emitters.