Exciton-Polariton Quantum Emulators
Speaker: Dr. Na Young Kim, Stanford
Series: Electrical Engineering Departmental Seminar
Location: Engineering Quadrangle B205
Date/Time: Thursday, February 23, 2012, 4:30 p.m. - 5:30 p.m.
Microcavity exciton-polaritons are hybrid light-matter quasi-particles arising from the mixed states between cavity photons and quantum well excitons. The inherent light-matter duality provides experimental advantages: the stimulated scattering among interacting particles and the small effective mass (~ 10-8 times the hydrogen atom) form coherent condensate states at high temperatures (e.g. 4 K in GaAs and room temperatures in GaN materials). In addition, the dynamics of exciton-polaritons are accessed by capturing the leaked photons out of the cavity due to the short lifetime. Utilizing coherence and open-dissipative nature of exciton-polariton condensates, we engineer a two-dimensional (2D) polariton-lattice system for investigating exotic quantum phase order. Via micro-photoluminescence measurements in both real and momentum spaces, we have observed d-orbital condensate states, vortex-antivortex phase order, massless Dirac dispersions in 2D square, honeycomb, and triangular lattices respectively. These results demonstrate that the polariton-lattice systems will be promising solid-state quantum emulators in the quest for better understanding strongly correlated materials and in the development of novel optoelectronic devices.
Na Young Kim is a Physical Science Research Associate in E. L. Ginzton Laboratorys Prof. Yamamoto group at Stanford University. She received her Ph.D. degree in Applied Physics from Stanford University for her dissertation on Correlated Electron Transport in One-dimensional Mesoscopic Conductors. She also holds B.S. degree in Physics from Seoul National University. She was a specially apponited researher at the Univerity of Tokyo and a postdoctoral researcher at Stanford University. She is a recipient of Outstanding Young Researcher Award 2012 from the Association of Korean Physicists in America. Her research interests are to construct solid-state quantum emulators for studying macroscopic quantum phases and to demonstrate unprecedented optoelectrical devices based on polariton condensates.