Detecting Photo-Induced Topological Edge States in a Graphene Nanoribbon Using Pump-Probe Spectroscopies

Recently, photo-induced topological edge states in low dimensional materials have attracted considerable attention due to the tunability of dispersion and topological properties using light. Here, we present a numerical study of various pump-probe spectroscopies for a graphene nanoribbon subject to circularly polarized pump light. In particular, we calculate time-resolved resonant inelastic x-ray scattering (tr-RIXS) for the graphene nanoribbon, which clearly resolves the pump-induced band gap and the edge states. These tr-RIXS features have a direct correspondence with Floquet states and the calculated time-resolved ARPES spectra. We also calculate the pump-probe optical conductivity and nonresonant Raman scattering, demonstrating that the signatures from the pump-induced gap and edge states also should be visible, especially at low energy. These pump-probe techniques provide powerful tools for detecting photo-induced topological states in low dimensional materials.