报告人：Prof. Yong-Shi Wu ( Department of Physics and Astronomy, University of Utah)

时间：2017年10月23日(周一)下午2:30

Abstract:To study gapped topological phases on​ ​open surfaces,​ ​we propose to addappropriately constructed boundary terms in the Hamiltonian. Our setting is​ ​exactly solvable discrete models, such as string-net models (and Witten-Dijkgraaf models). The full Hamiltonian in our approach yields a topologically protected, gapped energy spectrum, with the corresponding ​wave functions robust under topology-preserving transformations of the lattice. We explicitly present the wavefunctions of the ground states and boundary elementary excitations, as well ascreation and hopping operators of boundary quasi-particles.​ ​​We find that given a bulk topological order, the gapped boundary conditions are​ ​described by Frobenius algebras in its input data. ​Emergent topological properties of the ground states and boundary excitations are describedby (bi-) modules over Frobenius algebras。

简历：Yong-Shi Wu is presently a Distinguished Professor in the University of Utah. He graduated from Peking University in 1965 in a six-year system. Then he worked in the Institute of Physics and, later, of Theoretical Physics, Beijing, Chinese Academy of Sciences until 1981. In early eighties, he was a visiting scholar in the Institute for Theoretical Physics, State University of New York at Stony Brook, in the Institute of Advanced Study at Princeton and in the University of Washington at Seattle. He became, in 1984, Associate Professor in the University of Utah at Salt Lake City, and was promoted to a tenured full professor in 1987. He has been working extensively on geometric and topological aspects of theoretical particle and condensed matter physics. His achievements include Parisi-Wu stochastic quantization, non-abelian chiral gauge anomaly in any dimensions, braid group classification of quantum statistics in two-dimensional systems, general proof of quantized Hall conductance as topological invariant, existence of topological phase of photons, exactly solvable discrete models for topological quantum matter etc.

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