{
  "annotation_id": "678f382f-4b97-45e2-ba37-49b8fe90228a",
  "date_created": "2026-03-02T18:01:56.376000Z",
  "date_modified": "2026-03-02T18:01:56.376000Z",
  "file_hash": "d96f5c27e41eec01ae539ff27fb9ed1c8157401ef3582bb877341609da9de6d9",
  "private": false,
  "record": {
    "abstract": "We observe polarization-entanglement between four photons produced from a\nsingle down-conversion source. The non-classical correlations between the\nmeasurement results violate a generalized Bell inequality for four qubits. The\ncharacteristic properties and its easy generation with high interferometric\ncontrast make the observed four-photon state well-suited for implementing\nadvanced quantum communication schemes such as multi-party quantum key\ndistribution, secret sharing and telecloning.",
    "arxiv_id": "quant-ph/0302042",
    "authors": [
      "M. Eibl",
      "S. Gaertner",
      "M. Bourennane",
      "Ch. Kurtsiefer",
      "M. Zukowski",
      "H. Weinfurter"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevLett.90.200403",
    "title": "Experimental observation of four-photon entanglement from   down-conversion",
    "url": "https://arxiv.org/abs/quant-ph/0302042"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "f6eed554-8f9f-4145-82db-d0b4b28f81be",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}