报告主题： Quantum statistics and spacetime topology (量子统计与时空拓朴)
报告人：Dr. Juven Wang（Harvard University, Institute for Advanced Study in Princeton)
时间：2015年12月15日（周二)13:00
地点：校本部G309
主办部门：理学院物理系
邀请人：周世平教授
报告摘要：Topological invariances are useful tools to classify and characterize distinct states of condensed matter. Berry phase is one of such invariances, which can be generalized to the non-Abelian geometric matrix when energy eigenstates degenerate. For topological orders, specifically the many-body quantum states with bulk energy gap and with topology-dependent ground state degeneracy, the geometric matrix encodes the braiding statstics of energetic excitations. Apart from Berry phase, we can also use the wave function overlap to derive the braiding statistics data. We study particle and string statistics of 2+1 and 3+1 spacetime dimensions. We utilize aspects of quantum discreteness, spacetime topology to shed new insights for higher dimensional topological states of matter.