{
  "annotation_id": "aed4a82b-4ea6-4711-9b36-50bd76857d75",
  "date_created": "2026-03-02T18:01:46.130000Z",
  "date_modified": "2026-03-02T18:01:46.130000Z",
  "file_hash": "8a99bca28e4d9a6400327b3cbff6da2ecdbee9b527a0baa1ebb43a1802df9d4a",
  "private": false,
  "record": {
    "abstract": "We consider two apparently separated problems: in the first part of the paper\nwe study the concept of a scalable (approximate) programmable quantum gate\n(SPQG). These are special (approximate) programmable quantum gates, with nice\nproperties that could have implications on the theory of universal computation.\nUnfortunately, as we prove, such objects do not exist in the domain of usual\nquantum theory. In the second part the problem of noisy dense coding (and\ngeneralizations) is addressed. We observe that the additivity problem for the\nclassical capacity obtained is of apparently greater generality than for the\nusual quantum channel (completely positive maps): i.e., the latter occurs as a\nspecial case of the former, but, as we shall argue with the help of the\nnon-existence result of the first part, the former cannot be reduced to an\ninstance of the latter. We conclude by suggesting that the additivity problem\nfor the classical capacity of quantum channels, as posed until now, may\nconceptually not be in its appropriate generality.",
    "arxiv_id": "quant-ph/0108066",
    "authors": [
      "Andreas Winter"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1063/1.1498489",
    "journal_ref": "J. Math. Phys. 43(9):4341--4352, 2002.",
    "title": "Scalable programmable quantum gates and a new aspect of the additivity   problem for the classical capacity of quantum channels",
    "url": "https://arxiv.org/abs/quant-ph/0108066"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "3eb8601d-ed90-40e5-8c5e-68ba0515025f",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}