Theoretical study of near-field-induced local excitation dynamics

Abstract Near-field optics provides a revolutionary pathway to achieve high spatial resolution beyond the diffraction limit, which is unattainable with conventional optics. Furthermore, the strong localization of near-field light induces spatially nonuniform interactions with molecules, enabling access to forbidden quantum states and allowing for the control of light at the single-molecule level. To describe such nonuniform interactions between near-field light and molecules, we have developed a theoretical framework that goes beyond the dipole approximation. In this highlight review, we present the theoretical and computational frameworks developed primarily based on the multipolar Hamiltonian, along with a recent study that explores the electron dynamics of a single molecule induced by near-field excitation.