When the field strength of the light approaches the internal Coulomb force of materials, it can be used to control their electronic properties by inducing nonequilibrium quantum states. In this talk, the potential of such intense light-matter interactions in novel two dimensional materials will be discussed, with special emphasis on energy state control and extreme nonlinear optics. These experiments are enabled by the development of powerful mid-infrared light sources that can efficiently access internal resonance of electron-hole states, known as excitons, while avoiding sample damage that may result from direct photoabsorption. First part of the talk presents energy state control of two-dimensional materials beyond the perturbative regime, wherein a light-dressed replica and giant blue shift of excitonic states are characterized. The second part of the talk shows the unique application of artificially stacked materials to realize nonlinear optical processes of high-harmonic generation with enhanced efficiency. These findings demonstrate the exciting opportunities of harnessing quantum dynamics beyond perturbation in two-dimensional materials.

Yuki Kobayashi is an Assistant Professor in the Department of Chemistry at the University of Michigan. His research group at the U-M Chemistry is committed to developing new tools in spectroscopy, such as attosecond x-ray light sources, and using them to solve complex chemical/materials problems. Yuki graduated from the University of Tokyo with a degree in chemistry and from the University of Califoria, Berkeley in 2020 with a PhD in Chemistry with Stephen Leone and Daniel Neumark. He was a postdoctoral fellow with Tony Heinz, David Reis, and Shambhu Ghimire at Stanford/SLAC from 2020-2023, and joined the U-M faculty in 2023. Yuki was selected for UC President’s Lindau Nobel Laureate Meetings Fellow at University of California, and also for Urbanek-Chorodow Postdoctoral Fellow at Stanford University.