{
  "annotation_id": "6f01a5f6-2012-4984-8f61-90d999eb5dec",
  "date_created": "2026-03-02T18:01:55.384000Z",
  "date_modified": "2026-03-02T18:01:55.384000Z",
  "file_hash": "417f9cf71f649d16cee5f099b80f120c63477f19832cdb12e773b0072ca6293f",
  "private": false,
  "record": {
    "abstract": "Universal quantum cloning machines (UQCMs), sometimes called quantum cloners,\ngenerate many outputs with identical density matrices, with as close a\nresemblance to the input state as is allowed by the basic principles of quantum\nmechanics. Any experimental realization of a quantum cloner has to cope with\nthe effects of decoherence which terminate the coherent evolution demanded by a\nUQCM. We examine how many clones can be generated within a decoherence time. We\ncompare the time that a quantum cloner implemented with trapped ions requires\nto produce $M$ copies from $N$ identical pure state inputs and the decoherence\ntime during which the probability of spontaneous emission becomes\nnon-negligible. We find a method to construct an $N\\to M$ cloning circuit, and\nestimate the number of elementary logic gates required. It turns out that our\ncircuit is highly vulnerable to spontaneous emission as the number of gates in\nthe circuit is exponential with respect to the number of qubits involved.",
    "arxiv_id": "quant-ph/0210172",
    "authors": [
      "K. Maruyama",
      "P. L. Knight"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.67.032303",
    "journal_ref": "PRA 67, 032303 (2003)",
    "title": "Upper Bounds for the Number of Quantum Clones under Decoherence",
    "url": "https://arxiv.org/abs/quant-ph/0210172"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "e43074cf-bef9-4e64-aee3-88b3a38ad064",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}