Disclinations are ubiquitous lattice defects existing in almost all crystalline materials. In two-dimensional nanomaterials, disclinations lead to the warping and deformation of the hosting material, yielding non-Euclidean geometries. However, such geometries have never been investigated experimentally in the context of topological phenomena. Here, by creating the physical realization of disclinations in conical and saddle-shaped acoustic systems, we demonstrate that disclinations can lead to topologically protected bound modes in non-Euclidean surfaces. In the designed honeycomb sonic crystal for p-orbital acoustic waves, non-Euclidean geometry interplay with the p-orbital physics and the band topology, showing intriguing emergent features as confirmed by consistent experiments and simulations. Our study opens a pathway towards topological phenomena in non-Euclidean geometries that may inspire future studies on, e.g., electrons and phonons in nanomaterials with curved surfaces.
@article{arxiv.2201.10039,
title = {p-orbital disclination states in non-Euclidean geometries},
author = {Ying Chen and Yuhang Yin and Ze-Huan Zheng and Yang Liu and Zhi-Kang Lin and Jing Li and Jian-Hua Jiang and Huanyang Chen},
journal= {arXiv preprint arXiv:2201.10039},
year = {2022}
}