{
  "id": "1907.11619",
  "version": "v1",
  "published": "2019-07-26T15:20:52.000Z",
  "updated": "2019-07-26T15:20:52.000Z",
  "title": "Observation of non-Hermitian topology and its bulk-edge correspondence",
  "authors": [
    "Ananya Ghatak",
    "Martin Brandenbourger",
    "Jasper van Wezel",
    "Corentin Coulais"
  ],
  "comment": "7 pages including appendix. 4 figures",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.str-el",
    "quant-ph"
  ],
  "abstract": "Over the last few years, topological edge modes -- excitations that are localized at the materials' edges, yet that are characterized by a topological invariant defined from the material's bulk -- have enabled the creation of robust electronic, electromagnetic and mechanical transport properties across a wide range of systems, from cold atoms to metamaterials and geophysical flows. The advent of non-Hermitian topological systems -- wherein energy is not conserved -- has sparked considerable theoretical advances. In particular, novel topological phases that can only exist in non-Hermitian systems have been introduced. However, what are the properties of such phases and whether they can be observed have remained open questions. Here, we discover and observe experimentally a novel form of bulk-edge correspondence of a one-dimensional system characterized by a non-Hermitian topological phase. Namely, we find that a change in the non-Hermitian topological invariant corresponds to a change of localization of the topological edge mode. Using a quantum-to-classical analogy, we create a mechanical metamaterial with suitably designed interactions, where we observe experimentally the predicted bulk-edge correspondence, which in turn demonstrates the robustness of our findings. Our work sheds light on the nascent field of non-Hermitian topology and boosts metamaterials by opening new avenues to manipulate waves in unprecedented fashions.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-07-26T15:20:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "bulk-edge correspondence",
      "non-hermitian topology",
      "topological edge mode",
      "observation",
      "non-hermitian topological invariant corresponds"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}