{
  "annotation_id": "1245aa3e-7015-44cc-9fe5-93f73f550804",
  "date_created": "2026-03-02T18:02:31.103000Z",
  "date_modified": "2026-03-02T18:02:31.103000Z",
  "file_hash": "deadff24099c289ec00fe593055dead0d28078c68d50e972fb9ab8b42df8054b",
  "private": false,
  "record": {
    "abstract": "We verify a conjecture on the structure of higher-rank numerical ranges for a\nwide class of unitary and normal matrices. Using analytic and geometric\ntechniques, we show precisely how the higher-rank numerical ranges for a\ngeneric unitary matrix are given by complex polygons determined by the spectral\nstructure of the matrix. We discuss applications of the results to quantum\nerror correction, specifically to the problem of identification and\nconstruction of codes for binary unitary noise models.",
    "arxiv_id": "quant-ph/0608244",
    "authors": [
      "Man-Duen Choi",
      "John A. Holbrook",
      "David W. Kribs",
      "Karol Zyczkowski"
    ],
    "categories": [
      "quant-ph"
    ],
    "journal_ref": "Operators and Matrices 1, 409-426 (2007)",
    "title": "Higher-Rank Numerical Ranges of Unitary and Normal Matrices",
    "url": "https://arxiv.org/abs/quant-ph/0608244"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "d6b8e10f-9286-48cf-89ff-35d67c98c06f",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}