{
  "annotation_id": "efac9d1f-67a2-48f6-a067-bddca09c9fd2",
  "date_created": "2026-03-02T18:02:16.793000Z",
  "date_modified": "2026-03-02T18:02:16.793000Z",
  "file_hash": "076028d323bbe735604ef75c6f263fa443f598d864dead79984e6c2d95194654",
  "private": false,
  "record": {
    "abstract": "We experimentally demonstrate the first quantum system entangled in every\ndegree of freedom (hyperentangled). Using pairs of photons produced in\nspontaneous parametric downconversion, we verify entanglement by observing a\nBell-type inequality violation in each degree of freedom: polarization, spatial\nmode and time-energy. We also produce and characterize maximally hyperentangled\nstates and novel states simultaneously exhibiting both quantum and classical\ncorrelations. Finally, we report the tomography of a 2x2x3x3 system\n(36-dimensional Hilbert space), which we believe is the first reported photonic\nentangled system of this size to be so characterized.",
    "arxiv_id": "quant-ph/0507128",
    "authors": [
      "Julio T. Barreiro",
      "Nathan K. Langford",
      "Nicholas A. Peters",
      "Paul G. Kwiat"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevLett.95.260501",
    "journal_ref": "Phys. Rev. Lett. 95, 260501 (2005)",
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "title": "Generation of Hyperentangled Photons Pairs",
    "url": "https://arxiv.org/abs/quant-ph/0507128"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "cd72ccc1-fefb-4179-9bf7-8bdd03afbe72",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}