报告题目：Non-Hermitian exceptional points and their topological properties

报告时间：2025年9月18日（周四）15:30

报告地点：鼓楼校区唐仲英楼 B501

报  告 人：薛鹏 教授 北京计算科学研究中心

摘      要：Exceptional points (EPs) are a hallmark of non-Hermitian systems, distinguishing them from their Hermitian counterparts. At an EP, the Hamiltonian becomes defective-exhibiting coalescence of both eigenvalues and eigenstates. This singular spectral behavior leads to a range of novel phenomena with strong application potential and enriches the study of topological phases through unique topological structures.

While second-order EPs have been extensively studied, higher-order EPs offer greater diversity, complexity, and more profound physical manifestations. However, their experimental realization remains challenging due to the need for precise control over multiple parameters in high-dimensional non-Hermitian systems and direct spectral measurements.

To overcome these challenges, we leverage the controllable degrees of freedom of single photons to introduce various symmetries in a two-dimensional platform. We experimentally demonstrate third-order exceptional points, confirm the critical role of symmetry in their formation, and characterize their behavior under different symmetries. Moreover, we observe an isolated monopole-like third-order EP and investigate the non-Abelian topological braiding and associated phase transitions around it.

报告人简介：薛鹏，北京计算科学研究中心，教授，国家杰出青年基金获得者，王大珩光学奖中青年科技人员奖、谢希德物理奖获得者。1999年毕业于中国科学技术大学物理系，获得学士学位，并免试进入本校中科院量子信息重点实验室，2004年7月获得博士学位。之后赴奥地利因斯布鲁克大学物理系，以及加拿大卡尔加里大学物理系作为博士后从事量子信息的物理实现以及量子光学的基础研究工作，致力于利用量子行走实现普适的量子信息处理平台的研究工作。2009年回国。在国际顶级学术期刊包括：Nature Physics, Physical Review Letters等以第一/通信作者发表学术论文百余篇，文章被引用7000余次，单篇引用最高达800余次。