{
  "annotation_id": "09437c55-575a-4cd5-9111-1f6225eab79a",
  "date_created": "2026-03-02T18:02:41.169000Z",
  "date_modified": "2026-03-02T18:02:41.169000Z",
  "file_hash": "179ef48ec141d5875067436158a449b8dcc34ca7d9bbf56fad3c05fe42521dba",
  "private": false,
  "record": {
    "abstract": "We establish the best possible approximation to a perfect quantum cloning\nmachine which produces two clones out of a single input. We analyze both\nuniversal and state-dependent cloners. The maximal fidelity of cloning is shown\nto be 5/6 for universal cloners. It can be achieved either by a special unitary\nevolution or by a novel teleportation scheme. We construct the optimal\nstate-dependent cloners operating on any prescribed two non-orthogonal states,\ndiscuss their fidelities and the use of auxiliary physical resources in the\nprocess of cloning. The optimal universal cloners permit us to derive a new\nupper bound on the quantum capacity of the depolarizing quantum channel.",
    "arxiv_id": "quant-ph/9705038",
    "authors": [
      "D. Bruss",
      "D. P. DiVincenzo",
      "A. Ekert",
      "C. A. Fuchs",
      "C. Macchiavello",
      "J. A. Smolin"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.57.2368",
    "journal_ref": "PRA 57 (1998) 2368",
    "title": "Optimal Universal and State-Dependent Quantum Cloning",
    "url": "https://arxiv.org/abs/quant-ph/9705038"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "72fa579a-0410-41c8-bde5-368be7e0c258",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}