Hauptinhalt

Probing coherent exciton plasmon couplings using ultrafast two-dimensional electronic spectroscopy

Seminarvortrag

Veranstaltungsdaten

Abstract

Hybridization between excitonic quantum emitters and localized electromagnetic fields offers great potential for tailoring optoelectronic properties of quantum materials. For sufficiently large couplings, they give rise to oscillatory energy transfer between the light and matter constituents (Rabi oscillations) on a 10s of femtosecond time scale, forming new polaritonic eigen states. A powerful tool to access the coherent system evolution of such hybrid systems is ultrafast two-dimensional electronic spectroscopy (2DES). This coherent optical spectroscopy technique yields a series of energy-energy maps that correlate the excitation and emission energies as a function of the system evolution. 2DES is particularly sensitive to energy transfer dynamics and many-body interactions in condensed matter systems.

In my talk, I will first introduce ultrafast 2DES, including recent technological developments that we achieved in Oldenburg. I will then show how we used 2DES with 10-fs time resolution to follow the coherent polariton dynamics in two different plasmonic nanostructures that utilize different excitonic quantum emitters, i.e. Frenkel excitons of a molecular J-aggregated thinfilm or Wannier excitons of a transition metal dichalcogenide monolayer. Following the Rabi oscillation dynamics and evolution of the 2DES spectra, we were able to gain new insights into the underlying coupling mechanisms, the role of dark states and we could shed light onto the role of excitonic many-body interactions on the optical polariton nonlinearities. These findings highlight how ultrafast coherent (multidimensional) spectroscopy, by probing the system evolution before onset of decoherence, can give new insights into interactions and energy flow in hybrid quantum systems.