Multi-dimensional wave steering with higher-order topological phononic crystal  

基于高阶拓扑态的多维度声传输操控

作　　者：Changqing Xu Ze-Guo Chen Guanqing Zhang Guancong Ma Ying Wu 徐常清;陈泽国;张冠卿;马冠聪;吴莹(Division of Computer,Electrical and Mathematical Science and Engineering,King Abdullah University of Science and Technology(KAUST),Thuwal 23955-6900,Saudi Arabia;Department of Physics,Hong Kong Baptist University,Hong Kong,China)

机构地区：[1]Division of Computer,Electrical and Mathematical Science and Engineering,King Abdullah University of Science and Technology(KAUST),Thuwal 23955-6900,Saudi Arabia [2]Department of Physics,Hong Kong Baptist University,Hong Kong,China

出　　处：《Science Bulletin》2021年第17期1740-1745,M0003,共7页科学通报（英文版）

基　　金：supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No. OSR-2016-CRG5-2950;KAUST Baseline Research Fund BAS/1/1626-01-01;supported by the Hong Kong Research Grants Council (GRF 12302420, 12300419, ECS 22302718, CRF C6013-18G);the National Natural Science Foundation of China via the Excellent Young Scientist Scheme (Hong Kong & Macao) (#11922416);the Youth Program (#11802256);Hong Kong Baptist University (RC-SGT2/18-19/ SCI/006)。

摘　　要：The recent discovery and realizations of higher-order topological insulators enrich the fundamental studies on topological phases.Here,we report three-dimensional(3D)wave-steering capabilities enabled by topological boundary states at three different orders in a 3D phononic crystal with nontrivial bulk topology originated from the synergy of mirror symmetry of the unit cell and a non-symmorphic glide symmetry of the lattice.The multitude of topological states brings diverse possibilities of wave manipulations.Through judicious engineering of the boundary modes,we experimentally demonstrate two functionalities at different dimensions:2D negative refraction of sound wave enabled by a firstorder topological surface state with negative dispersion,and a 3D acoustic interferometer leveraging on second-order topological hinge states.Our work showcases that topological modes at different orders promise diverse wave steering applications across different dimensions.高阶拓扑绝缘体展现出新奇的体-边对应关系,即d维n阶拓扑绝缘体具有(d-n)维拓扑保护的边界态.近年来,高阶拓扑绝缘体的相关物理概念已经被拓展到光子晶体、声子晶体等体系中.本文着重讨论声波高阶拓扑绝缘体的边界态在波调控中的具体应用.作者利用原胞的镜像对称性和滑移对称性,设计出一种拓扑非平庸的三维声子晶体.该声子晶体的体能带可由非平庸的量子化体极化表征,从而在不同维度的边界上存在拓扑保护的二维表面态、一维棱态、零维角态.作者对二维表面态和一维棱态加以利用,在实验上实现了拓扑边界态主导的声波在不同维度上的传播操控.具体来说,通过设计二维表面态的色散的设计,实现了声波的负折射;通过利用不同方向上的一维棱态传输,实现了三维里的声干涉.这些结果展示了高阶拓扑绝缘体在操控波传播方面具有独特的应用前景.

关 键 词：Higher-order topological insulator Topological states Negative refraction 3D acoustic interferometer 

分 类 号：O469[理学—凝聚态物理]