{
  "abstract": "Chern insulators have optical properties that are strikingly different than ordinary chiral media. Unlike the natural optical activity of the latter, which is a finite-wavelength effect arising from spatial dispersion, the optical activity of a Chern insulator is already present in the long-wavelength limit, and exhibits a striking directional asymmetry in the propagation of circularly polarized light. We study this unnatural optical activity using a recently developed field theory for Chern insulators. For bulk Chern insulators, we derive the normal-incidence transmission and reflection coefficients of multilayer structures, identify the associated Faraday and Kerr angles, and show that these optical rotations provide a direct optical signature of topology at low frequencies. We also show that an interface between bulk Chern insulators can act as a kind of mirror, completely reflecting light at normal incidence when the Chern invariants have opposite signs. Moving to a more realistic model of a two-dimensional current sheet, we study the Faraday and Kerr effects in a thin film of $\\mathrm{Mn}\\mathrm{Bi}_2\\mathrm{Te}_4$ in its Chern insulator phase. The predicted rotations are many orders of magnitude larger than those of optically active media of comparable thickness that are topologically trivial.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.19284",
  "author_total": 2,
  "authors": [
    {
      "name": "Jason G. Kattan"
    },
    {
      "name": "J. E. Sipe"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1mv7g638042bh.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.19284",
  "fulltext_url": null,
  "id": "1mv7g638042bh",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.19284",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mes-hall"
    ],
    [
      "arxiv",
      "physics.optics"
    ],
    [
      "openalex",
      "3107|Topological Materials and Phenomena"
    ]
  ],
  "openalex": "W7222087900",
  "pdf_url": "https://arxiv.org/pdf/2610.19284",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1mv7g638042bh.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:31Z",
      "native_id": "2610.19284",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.19284"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mes-hall",
      "subfield": "condensed-matter"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    }
  ],
  "title": "Chern insulator optics",
  "title_text": "Chern insulator optics",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:31Z",
  "url": "https://research.draconitic.com/paper/1mv7g638042bh",
  "venue": "arXiv",
  "versions": []
}