Wu Junpeng, Zheng Riyi, Liang Jialuo, Ke Manzhu, Lu Jiuyang, Deng Weiyin, Huang Xueqin, Liu Zhengyou
School of Physics and Optoelectronics and State Key Laboratory Luminescent Materials and Devices, <a href="https://ror.org/0530pts50">South China University of Technology</a>, Guangzhou 510640, China.
Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education and School of Physics and Technology, <a href="https://ror.org/033vjfk17">Wuhan University</a>, Wuhan 430072, China.
Phys Rev Lett. 2024 Sep 20;133(12):126601. doi: 10.1103/PhysRevLett.133.126601.
As a distinctive feature unique to non-Hermitian systems, non-Hermitian skin effect displays fruitful exotic phenomena in one or higher dimensions, especially when conventional topological phases are involved. Among them, hybrid skin-topological effect is theoretically proposed recently, which exhibits anomalous localization of topological boundary states at lower-dimensional boundaries accompanied by extended bulk states. Here, we experimentally realize the hybrid skin-topological effect in a non-Hermitian phononic crystal. The phononic crystal, before tuning to be non-Hermitian, is an ideal acoustic realization of the Kane-Mele model, which hosts gapless helical edge states at the boundaries. By introducing a staggered distribution of loss, the spin-dependent edge modes pile up to opposite corners, leading to a direct observation of the spin-dependent hybrid skin-topological effect. Our Letter highlights the interplay between topology and non-Hermiticity and opens new routes to non-Hermitian wave manipulations.
作为非厄米系统独有的一个显著特征，非厄米趋肤效应在一维或更高维度中展现出丰富多样的奇异现象，特别是当涉及到传统拓扑相时。其中，混合趋肤 - 拓扑效应是最近在理论上提出的，它表现为拓扑边界态在低维边界处的反常局域化，并伴有扩展的体态。在此，我们在非厄米声子晶体中通过实验实现了混合趋肤 - 拓扑效应。在调谐为非厄米之前，该声子晶体是凯恩 - 梅勒模型的理想声学实现，其在边界处存在无隙螺旋边缘态。通过引入交错分布的损耗，自旋相关的边缘模式堆积到相对的角上，从而直接观测到了自旋相关的混合趋肤 - 拓扑效应。我们的这篇论文突出了拓扑与非厄米性之间的相互作用，并为非厄米波操控开辟了新途径。
