Title：Explore light-matter interaction in quantum materials

Speaker：Hao Chu, Max Planck-UBC-UTokyo Cente

Date：June 19th，09：30am

Meeting Link：https://meetinpah9KVTaAGSy; Meeting ID: 138 227 088g.tencent.com/s/？

Abstract：From Newton’s prism experiment to Maxwell’s equations to modern day spectroscopy, light has always been an integral and defining part of physics. In recent years, the development of ultrafast light sources is again re-defining approaches and concepts in physics, chemistry and materials research. The time axis is becoming an empirical dimension to visualize and manipulate interactions in solids and molecules, in many cases yielding more clarifying pictures than the equilibrium thermodynamic counterparts. Novel light-induced phases, not necessarily attainable in equilibrium, have also been demonstrated, promising future semiconductor technology beyond electric field switching. In addition, the intense electric field of ultrafast light sources also enables nonlinear optical studies, often yielding insight into physical systems beyond what linear response may tell.

In my talk, I will discuss how nonlinear and ultrafast spectroscopy is being applied to investigate correlated materials including cuprate high-Tc superconductors and iridate perovskites. I will discuss 1) how nonlinear optics can be used to characterize the symmetry of solids and discover hidden/multipolar order. 2) how time-resolved optics can be used to investigate subtle insulator-to-metal transition and uncover fluctuating/dynamic collective modes. 3) how intense terahertz pulse can couple to the superconducting condensate and drive collective oscillation of the condensate. 4) how a fluctuating charge density wave may also reveal itself in the nonlinear terahertz response. And finally 5) in the case of van der Waals materials, how nonlinear optics may be used to detect long range antiferromagnetic order towards the 2D limit.