报告时间：7月6日下午4点

报告地点：近代物理系210会议室

报告人： 新加坡国立大学 王清海 高级讲师

报告题目：Geometry Phases in Nonunitary Cyclic Dynamics and Piecewise Following

报告摘要：The time evolution of periodically driven non-Hermitian systems is in general nonunitary but can be stable.  In this talk, I will examine the adiabatic following dynamics in periodically driven non-Hermitian systems. I will show the possibility of piecewise adiabatic following interrupted by hopping between instantaneous system eigenstates.  The mathematical origin of this new discovery is the Stokes phenomenon. I will show that the piecewise following is a genuine critical behavior and the phase diagram in the parameter space is determined.  Interestingly, the critical boundary for piecewise adiabatic following is found to be unrelated to the domain for exceptional points. To characterize the adiabatic following dynamics, I will also advocate a simple definition of the Aharonov-Anandan (AA) phase for non-unitary cyclic dynamics, which always yields real AA phases.  In the slow driving limit, the AA phase reduces to the Berry phase if adiabatic following persists throughout the driving without hopping, but oscillates violently and does not approach any limit in cases of piecewise adiabatic following.

报告人简历：

1992-1996，中国科技大学，理论物理学士

1996-1999，中国科技大学，理论物理硕士

1999-2005，Washington University in St. Louis (USA)，物理博士

2005-2007，University of Connecticut (USA)，博士后研究员

2007-2008，Singapore Management University，代课老师，研究员

2008-2011，National University of Singapore，讲师

2012-现在，National University of Singapore，高级讲师