{
  "annotation_id": "a6fd565a-b121-4737-bfbb-9abb79dd8c1c",
  "date_created": "2026-03-02T18:02:27.566000Z",
  "date_modified": "2026-03-02T18:02:27.566000Z",
  "file_hash": "4d56787bb1b48a4053889f9ec6778c25eed04eac280a279051b681497ee2edce",
  "private": false,
  "record": {
    "abstract": "In quantum physics, the density operator completely describes the state.\nInstead, in classical physics the mean value of every physical quantity is\nevaluated by means of a probability distribution. We study the possibility to\ndescribe pure quantum states and events with classical probability\ndistributions and conditional probabilities and prove that the distributions\ncan not be quadratic functions of the quantum state. Some examples are\nconsidered. Finally, we deal with the exponential complexity problem of quantum\nphysics and introduce the concept of classical dimension for a quantum system.",
    "arxiv_id": "quant-ph/0604155",
    "authors": [
      "Alberto Montina"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevLett.97.180401",
    "journal_ref": "Phys. Rev. Lett. 97, 180401 (2006)",
    "title": "A condition for any realistic theory of quantum systems",
    "url": "https://arxiv.org/abs/quant-ph/0604155"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "d55e0857-101b-4fea-812c-c41eef4e89e8",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}