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报告题目： Floquet topological phase transition: Control of quantum matter by laser 报告人： Prof. Takashi Oka, Department of Applied Physics, University of Tokyo 报告时间： 2014-2-20 10:00 报告地点：理科楼三楼报告厅摘要： The effect of strong laser on the topology of many-electron systems is becoming a hot topic [1,2,3]. Recently, a theoretical proposal was made in two dimensional Dirac systems where an application of circularly polarized light was shown to turn the system into a quantum Hall state with a non-trivial photo-induced Chern number and an emergence of edge channels [1,2]. One can see this as a dynamical realization of the Haldane model of a quantum Hall state without Landau levels [4]. This effect can be understood with the help of the Floquet theory of driven quantum systems, where the circularly polarized light plays the role similar to the next nearest hopping with a nontrivial phase factor in the Haldane model. This proposal applies to a broad class of multi-band systems including graphene, graphite and surface states of topological insulators as well as cold atoms in optical lattices with synthetic gauge fields. References: [1] T. Oka and H. Aoki: Phys. Rev. B 79, 081406 (2009).
[2] T. Kitagawa, T. Oka, A. Brataas, L. Fu, E. Demler: Phys. Rev. B 84, 235108 (2011).
[3] N. H. Lindner, G. Refael, V. Galitski: Nat. Phys. 7 490 (2011).
[4] F. D. M. Haldane: Phys. Rev. Lett. 61 2015 (1988). 个人简介： Dr. Oka received his B.S. (2000) and Ph.D. (2005) in physics both from the Department of Physics at the University of Tokyo. Then he became a postdoctoral researcher at National Institute of Advanced Industrial Science and Technology. From 2006 to 2012, he was an assistant professor in the Department of Physics, University of Tokyo. He is currently a lecturer in the Department of Applied Physics, University of Tokyo. His research field is condensed matter theory, and his main research interests include non-equilibrium phase transitions, Floquet topological phase transition, dielectric breakdown in Mott insulators, High-Tc superconductors, and application of AdS/CFT.