Realization of a quadrupole topological insulator phase in a gyromagnetic photonic crystal  

作　　者：Peiheng Zhou Gui-Geng Liu Zihao Wang Shuwei Li Qindong Xie Yunpeng Zhang Subhaskar Mandal Xiang Xi Zhen Gao Longjiang Deng Baile Zhang 

机构地区：[1]National Engineering Research Center of Electromagnetic Radiation Control Materials,Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education,University of Electronic Science and Technology of China,Chengdu 611731,China [2]Division of Physics and Applied Physics,School of Physical and Mathematical Sciences,Nanyang Technological University,Singapore 637371,Singapore [3]School of Electrical Engineering and Intelligentization,Dongguan University of Technology,Dongguan 523808,China [4]Department of Electronic and Electrical Engineering,Southern University of Science and Technology,Shenzhen 518055,China [5]Centre for Disruptive Photonic Technologies,The Photonics Institute,Nanyang Technological University,Singapore 639798,Singapore

出　　处：《National Science Review》2024年第11期41-47,共7页国家科学评论（英文版）

基　　金：supported by the National Natural Science Foundation of China(52022018 and 52021001);Nanyang Technological University was supported by the Singapore National Research Foundation Competitive Research Program(NRF-CRP23-2019-0007).

摘　　要：The field of topological photonics was initiated with the realization of a Chern insulator phase in a gyromagnetic photonic crystal(PhC)with broken time-reversal symmetry(T),hosting chiral edge states that are topologically protected propagating modes.Along a separate line of research,a quadrupole topological insulator was the first higher-order topological phase supporting localized corner states,but has been so far limited to T-invariant systems,as T is a key ingredient in early models.Here we report the realization of a quadrupole topological insulator phase in a gyromagnetic PhC,as a consequence of topological phase transition from the previously demonstrated Chern insulator phase.The phase transition has been demonstrated with microwave measurements,which characterize the evolution from propagating chiral edge states to localized corner states.We also demonstrate the migration of topological boundary states into the continuum,when the gyromagnetic PhC is magnetically tuned.These results extend the quadrupole topological insulator phase into T-broken systems,and integrate topologically protected propagating and localized modes in a magnetically tunable photonic crystal platform.

关 键 词：quadrupole topological insulator time-reversal symmetry breaking corner states topological phase transition 

分 类 号：O431.2[机械工程—光学工程]