{
  "id": "1806.09418",
  "version": "v1",
  "published": "2018-06-25T12:30:49.000Z",
  "updated": "2018-06-25T12:30:49.000Z",
  "title": "Acoustic higher-order topological insulator on a Kagome lattice",
  "authors": [
    "Haoran Xue",
    "Yahui Yang",
    "Fei Gao",
    "Yidong Chong",
    "Baile Zhang"
  ],
  "comment": "15 pages, 4 figures",
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "High-order topological insulators (TIs) are a family of recently-predicted topological phases of matter obeying an extended topological bulk-boundary correspondence principle. For example, a two-dimensional (2D) second-order TI does not exhibit gapless one-dimensional (1D) topological edge states, like a standard 2D TI, but instead has topologically-protected zero-dimensional (0D) corner states. So far, higher-order TIs have been demonstrated only in classical mechanical and electromagnetic metamaterials exhibiting quantized quadrupole polarization. Here, we experimentally realize a second-order TI in an acoustic metamaterial. This is the first experimental realization of a new type of higher-order TI, based on a breathing Kagome lattice, that has zero quadrupole polarization but nontrivial bulk topology characterized by quantized Wannier centers (WCs). Unlike previous higher-order TI realizations, the corner states depend not only on the bulk topology but also on the corner shape; we show experimentally that they exist at acute-angled corners of the Kagome lattice, but not at obtuse-angled corners. This shape dependence allows corner states to act as topologically-protected but reconfigurable local resonances.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2018-06-25T12:30:49.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "acoustic higher-order topological insulator",
      "kagome lattice",
      "topological bulk-boundary correspondence principle",
      "exhibiting quantized quadrupole polarization",
      "metamaterials exhibiting quantized quadrupole"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 15,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}