{
  "abstract": "The bulk-boundary correspondence establishes a fundamental connection between bulk band topology and the emergence of boundary states, underpinning topological phenomena across electronic, acoustic, photonic, and many other wave systems. A broad class of singular flatband systems, however, exhibits an unconventional form of bulk-boundary correspondence, in which robust boundary modes (RBMs) originate from flatband-touching points (FBTPs) and the real-space topology associated with incomplete sets of compact localized states (CLSs), rather than conventional momentum-space bulk topological invariants. To date, experimental studies of such boundary modes have been limited to systems hosting lower-order FBTPs. Here, we experimentally demonstrate unconventional bulk-boundary correspondence in a photonic cross-bedded Kagome-like lattice featuring a higher-order FBTP formed by the touching of two degenerate flatbands and a dispersive band. Using continuous-wave laser writing, we observe shape-preserving propagation of both bulk CLSs and boundary RBMs. Remarkably, unlike previously reported flatband systems, the RBMs retain their boundary localization under input-field perturbations involving both singular and nonsingular CLSs, revealing an unconventional boundary response associated with the higher-order FBTP in this lattice. Our results establish the Kagome-like lattice as a new platform for exploring flatband physics and unconventional bulk-boundary correspondence, with potential applications in wave localization, flatband lasers, and other emerging topological photonic devices.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.29251",
  "author_total": 5,
  "authors": [
    {
      "name": "Limin Song"
    },
    {
      "name": "Jianqi Xiong"
    },
    {
      "name": "Liqin Tang"
    },
    {
      "name": "Daohong Song"
    },
    {
      "name": "Zhigang Chen"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/d56egbq5rbk4p.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.29251",
  "fulltext_url": null,
  "id": "d56egbq5rbk4p",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.29251",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "arxiv",
      "physics.optics"
    ],
    [
      "openalex",
      "3107|Topological Materials and Phenomena"
    ]
  ],
  "openalex": "W7223238495",
  "pdf_url": "https://arxiv.org/pdf/2610.29251",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/d56egbq5rbk4p.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:19Z",
      "native_id": "2610.29251",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.29251"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    }
  ],
  "title": "Higher-Order Flatband-Touching Points Mediate Unconventional Bulk-Boundary Correspondence",
  "title_text": "Higher-Order Flatband-Touching Points Mediate Unconventional Bulk-Boundary Correspondence",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:19Z",
  "url": "https://research.draconitic.com/paper/d56egbq5rbk4p",
  "venue": "arXiv",
  "versions": []
}