Weiner Matthew, Ni Xiang, Li Mengyao, Alù Andrea, Khanikaev Alexander B
Department of Electrical Engineering, Grove School of Engineering, City College of the City University of New York, 140th Street and Convent Avenue, New York, NY 10031, USA.
Physics Program, Graduate Center of the City University of New York, New York, NY 10016, USA.
Sci Adv. 2020 Mar 27;6(13):eaay4166. doi: 10.1126/sciadv.aay4166. eCollection 2020 Mar.
Classical wave systems have constituted an excellent platform for emulating complex quantum phenomena, such as demonstrating topological phenomena in photonics and acoustics. Recently, a new class of topological states localized in more than one dimension of a -dimensional system, referred to as higher-order topological (HOT) states, has been reported, offering an even more versatile platform to confine and control classical radiation and mechanical motion. Here, we design and experimentally study a 3D topological acoustic metamaterial supporting third-order (0D) topological corner states along with second-order (1D) edge states and first-order (2D) surface states within the same topological bandgap, thus establishing a full hierarchy of nontrivial bulk polarization-induced states in three dimensions. The assembled 3D topological metamaterial represents the acoustic analog of a pyrochlore lattice made of interconnected molecules, and is shown to exhibit topological bulk polarization, leading to the emergence of boundary states.
经典波系统构成了一个用于模拟复杂量子现象的出色平台，比如在光子学和声学中展示拓扑现象。最近，一类新的拓扑态被报道，这类拓扑态局域于一维系统的多个维度，被称为高阶拓扑（HOT）态，它为限制和控制经典辐射及机械运动提供了一个更加通用的平台。在此，我们设计并通过实验研究了一种三维拓扑声学超材料，它在同一拓扑带隙内支持三阶（0维）拓扑角态以及二阶（1维）边缘态和一阶（2维）表面态，从而在三维空间中建立了由非平凡体极化诱导态构成的完整层级结构。组装好的三维拓扑超材料代表了由相互连接的分子构成的烧绿石晶格的声学类似物，并且显示出具有拓扑体极化，进而导致边界态的出现。
