Speaker
Description
Strong coupling between electromagnetic radiation and matter is highly promising for tailoring optoelectronic and transport properties of functional materials, with potential applications ranging from organic photovoltaics to nanophotonics and quantum technologies. Strong coupling manifests in peak splittings in the optical spectra and ultrafast Rabi oscillations in the dynamics. The underlying processes involve a complex interplay of electronic, vibrational, and photonic degrees of freedom and occur on ultrashort, few 100s-fs timescales, thus demanding techniques combining high time resolution and the ability to unravel couplings. Here, we present some of our recent results using broadband two-dimensional electronic spectroscopy to probe couplings and track their quantum dynamics. In molecular aggregates of quadrupolar dyes on a gold nanoslit array, where molecular excitons are collectively coupled to spatially structured plasmonic fields, we observe coherent oscillations arising from plasmon-induced coherent exciton population transfer over mesoscopic distances at room temperature. In halide perovskites crystals, we demonstrate exciton Rabi oscillations driven by coherent phonon fields which behave essentially as the coupling of excitons to a field mode in an optical cavity. We show that even internal fields induced by low frequency coherent lattice motions can transiently control the ultrafast optical response in these materials. Our results suggest strategies for controlling ultrafast coherent dynamics in functional materials. Timmer et al, Nature Commun. 14, 8035 (2023); Nguyen et al, Nature Commun. 14, 1047 (2023)
