Mixed Quantum-Classical Electrodynamics: Novel Approaches for Photoexcitation and Spectroscopy

Mixed quantum-classical theory (quantum matter plus classical fields) is developed to enable accurate and feasible treatment of strong light-matter interactions for molecules and materials. The dynamics of a quantum system interacting with lights usually involves multiple timescales (nuclear motions versus optical frequencies), heterogeneous environments (cavities or nanoparticles), and emerging quantum effects (hybridization of electronic and photonic excitations), rendering traditional semiclassical electrodynamics difficult to capture many exciting phenomena. I propose new semiclassical models to recover quantum features of the photon field and investigate a variety of dynamical processes ranging from spontaneous emission, Raman scattering, resonance fluorescence, to resonant energy transfer. The results highlight the fact that, when properly designed, semiclassical electrodynamics can provide affordable approaches for modeling strong light-matter coupling phenomena, especially in the fields of nanoplasmonics and quantum optics.