OSC Colloquium: Shambhu Ghimire, "High-harmonic Spectroscopy of Quantum Materials"

Abstract(s): 

High-harmonic spectroscopy is a novel spectroscopic approach based on the microscopic mechanism for high-order harmonic generation (HHG). In the gas phase, it has been shown successfully that this approach can probe the structure and dynamics of atoms and small molecules. The understanding of the HHG mechanism that was developed in the nineties and the subsequent advances have led up to this possibility [1]. Solid-state HHG was however realized just about a decade ago [2]. In experiments, harmonics up to 25th order were observed from bulk zinc oxide crystals subjected to intense mid-infrared laser fields [2]. Since then, there has been rapidly growing interest in investigating the solid-state HHG process, particularly to explore its potential as an ultrafast all-optical probe of materials, as well as its perspective as a compact attosecond light source [3]. Just within a decade, solid-state HHG has emerged as one of the frontiers of attosecond science, along with a promising impact on materials science, particularly on quantum materials. In this talk, I will give a brief overview of this emerging field and present our latest results in atomically thin two-dimensional crystals [4] and three-dimensional topological insulators [5].

Speaker Bio(s): 

Dr. Shambhu Ghimire is a Lead Scientist and a Principal Investigator at the Stanford PULSE Institute, SLAC National Accelerator Laboratory. He is a recipient of the prestigious Young Investigator award from the U.S. Department of Energy (2014-2019). His research interests are on Attosecond Science and Nonlinear Optics. He received a Ph.D. degree in physics from Kansas State University in 2007 and a postdoctoral training from University of Michigan before joining SLAC in 2009.