报告题目：Non-Abelian Operations with Classical Waves

报告人：马冠聪副教授   香港浸会大学

报告时间：2021年12月28日（周二）10：30

报告地点：理六栋302    邀请人：张善超

报告内容：

        Non-Abelian-based theories are one of the foundations of modern physics. For example, non-Abelian braiding realized by the dynamic winding of anyons is widely considered an important candidate of quantum computers. Operations defined by non-Abelian groups are non-commutative in character, meaning that the outcomes of sequential operations depend on their orders. Non-Abelian processes are mathematically captured by unitary matrices, which can manifest as a Berry-phase matrix that connects holonomic adiabatic evolutions of multiple states in parameter space. Because Berry phase is pervasive in a wide variety of systems, non-Abelian operations are realizable in classical waves such as sound and light. In this talk, I will present our recent findings in classical-wave non-Abelian operations. First, I will show the realization of non-Abelian braiding in acoustics and photonics. Here, the braiding operations are implemented using coupled waveguide arrays, which are adiabatically modulated to enforce a multi-state Berry-phase matrix that swaps of modal dwell sites. The non-Abelian characteristics are revealed by switching the order of two distinct braiding operations involving three modes. Second, I will show that non-Hermitian systems are also capable of realizing non-Abelian operations. This is because the evolution of non-Hermitian eigenstates is confined by a complex Riemannian manifold, which naturally permits state exchange. The operations comprising a non-Abelian dihedral group of degree-3 are realized in a three-state acoustic non-Hermitian system as an example.

专家简介：

      马冠聪，香港浸会大学物理系副教授，现任香港物理协会理事会成员。2019年获得国家优青（港澳），2021年获中国科协 “十大科技新锐人物”。 他本科毕业于华南理工大学应用物理系，2012年在香港科技大学物理学系获得博士学位。2012-2017年在香港科技大学物理系和高等研究院任博士后研究员。研究兴趣主要集中于人工体系中的拓扑物理、非厄米物理、以及声波超材料等。在Science, Nature Materials, Nature Physics, Nature Communications, PNAS, Physical Review X, Physical Review Letters等期刊发表论文40余篇，总引用数>4700。于2020、2021年被科睿唯安列入“全球前2%科学家”。其中2016年在Science Advances发表关于声波超材料的综述文章，2019 年在Nature Reviews Physics发表关于拓扑声学的综述文章并入选Nature杂志社“40 years of quantum Hall effect”专题选集。受邀于META、Metamaterials、PIERS国际知名会议做邀请报告10余次，并多次担任META、Metamaterials等会议的关于声波超材料和声子晶体的分会场组织者、会场主席。研究成果亦先后获得美国、中国等专利授权共9项，部分已实现转化。