Extreme Light-Matter Interactions in Two Dimensions: Yuki Kobayashi, Postdoctoral Fellow, Stanford University

Event time: 
January 19, 2023 - 10:30am to 12:00pm
Location: 
Sterling Chemistry Laboratory (SCL) See map
Event description: 

Location: SCL 160

Join the Yale Chemistry Department for a Physical Chemistry seminar with Yuki Kobayashi, postdoctoral fellow at Stanford University.

Abstract:

Spectroscopy is a tool for scientists to see quantum states of materials with light. 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, I will discuss the potential of such intense light-matter interactions in novel two-dimensional materials, monolayer transition-metal dichalcogenides (TMDs), 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. In the first part of the talk, I will present energy state control of monolayer TMDs beyond the perturbative regime, wherein a light-dressed replica and giant blue shift of excitonic states are characterized. In the second part of the talk, I will demonstrate the unique application of artificially stacked TMDs 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 novel two-dimensional materials.

About Yuki Kobayashi:

Yuki Kobayashi received his B.S. in Chemistry from University of Tokyo in 2015, and then his Ph.D. in Chemistry from University of California, Berkeley in 2020. For his dissertation, he worked under Prof. Stephen R. Leone and Prof. Daniel M. Neumark on attosecond spectroscopy of chemical dynamics. He is currently an Urbanek-Chodorow Postdoctoral Fellow at Stanford PULSE Institute in the group of Prof. Tony F. Heinz, Prof. David A. Reis, and Dr. Shambhu Ghimire, working on nonequlibrium dynamics in two-dimensional materials. Yuki’s research involves studying quantum nature of reaction dynamics in chemical and materials systems through advanced spectroscopy, as well as the development of theoretical frameworks. For his work, Yuki has been selected as the UC President’s Lindau Nobel Laureate Meetings Fellow.