{
  "annotation_id": "4cf70093-811d-4014-8fc2-f7e726065eda",
  "date_created": "2026-03-02T18:02:27.178000Z",
  "date_modified": "2026-03-02T18:02:27.178000Z",
  "file_hash": "9bd2ba6c3f0beb224ab470b7c55ed29580bda4275116ac6cb4dff5fdc3f4f8fc",
  "private": false,
  "record": {
    "abstract": "We compare two physical systems: polarization degrees of freedom of a\nmacroscopic light beam and the Josephson junction (JJ) in the \"charge qubit\nregime\". The first system obviously cannot carry genuine quantum information\nand we show that the maximal entanglement which could be encoded into\npolarization of two light beams scales like 1/(photon number). Two theories of\nJJ, one leading to the picture of \"JJ-qubit\" and the other based on the\nmean-field approach are discussed. The later, which seems to be more\nappropriate, implies that the JJ system is, essentially, mathematically\nequivalent to the polarization of a light beam with the number of photons\nreplaced by the number of Cooper pairs. The existing experiments consistent\nwith the \"JJ-qubit\" picture and the theoretical arguments supporting, on the\ncontrary, the classical model are briefly discussed. The Franck-Hertz-type\nexperiment is suggested as an ultimate test of the JJ nature.",
    "arxiv_id": "quant-ph/0606242",
    "authors": [
      "Robert Alicki"
    ],
    "categories": [
      "quant-ph"
    ],
    "title": "False qubits?: Polarization of light and Josephson junction",
    "url": "https://arxiv.org/abs/quant-ph/0606242"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "15f04ad0-bdfc-477d-bd54-529f266daadb",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}