Title:Cavity-Dressed Quantum Matter

Speaker: Prof. Junichiro Kono，Rice University

Time:2024-10-23 16:00pm

Venue: C302,New Science Building

Abstract:There has been a growing realization that the properties of a material can be modified just by placing it in an optical cavity. The quantum vacuum fields surrounding the material inside the cavity can cause nonintuitive modifications of electronic states through ultrastrong vacuum–matter coupling, producing a vacuum-dressed material with novel properties. Existing theoretical predictions include cavity-enhanced, cavity-induced, and cavity-mediated enhancement of electron-phonon coupling and superconductivity, electron pairing, anomalous Hall effect, ferroelectric phase transitions, quantum spin liquids, and photon condensation. Achieving the so-called ultrastrong coupling (USC) regime is a prerequisite for observing these effects, which arise when the interaction energy becomes a significant fraction of the bare photonic mode and matter excitation frequencies. Most intriguingly, when a material is ultrastrongly coupled with cavity-enhanced vacuum electromagnetic fields, its ground state will contain virtual photons. This nonperturbative virtual driving without external fields can lead to phase transitions in thermal equilibrium. This talk will describe our recent studies of USC phenomena in various solid-state cavity quantum electrodynamics systems in search of such vacuum-induced phases of matter. We utilize the phenomenon of Dicke cooperativity, i.e., many-body enhancement of light–matter interaction, to explore quantum-optical strategies for creating, controlling, and utilizing novel phases in condensed matter enabled by the quantum vacuum.

Bio:Prof. Junichiro Kono received his B.S. and M.S. degrees in applied physics from the University of Tokyo in 1990 and 1992, respectively, and completed his Ph.D. in physics at the State University of New York at Buffalo in 1995. He was a postdoctoral research associate in condensed matter physics at the University of California, Santa Barbara, from 1995 to 1997 and worked as the W. W. Hansen Experimental Physics Laboratory Fellow in the Department of Physics at Stanford University from 1997 to 2000. He joined the Department of Electrical and Computer Engineering of Rice University in 2000 as an Assistant Professor and was promoted to Associate Professor in 2005 and to Professor in 2009. He is currently Karl F. Hasselmann Chair in Engineering, serving as a Professor in the Departments of Electrical & Computer Engineering, Physics & Astronomy, and Materials Science & Nanoengineering, as well as the Director of the Smalley-Curl Institute at Rice University.