{
  "annotation_id": "416cf3c9-78d8-4a40-afeb-21c375dca923",
  "date_created": "2026-03-02T18:01:42.427000Z",
  "date_modified": "2026-03-02T18:01:42.427000Z",
  "file_hash": "36c8e1a2f0c336527eda8ef58531010c655a0034bf10b0454915f12dcb26a336",
  "private": false,
  "record": {
    "abstract": "Bu\\v{z}ek and Hillery proposed a universal quantum-copying machine (UQCM)\n(i.e., transformation) to analyze the possibility of cloning arbitrary states.\nThe UQCM copies quantum-mechanical states with the quality of its output does\nnot depend on the input. We propose a slightly different transformation to\nanalyze a restricted set of input states. We impose the conditions (I) the\ndensity matrices of the two output states are the same, and that (II) the\ndistance between input density operator and the output density operators is\ninput state independent. Using Hilbert-Schmidt norm and Bures fidelity, we show\nthat our transformation can achieves the bound of the fidelity.",
    "arxiv_id": "quant-ph/0012033",
    "authors": [
      "Heng Fan",
      "Xiang-Bin Wang",
      "Keiji Matsumoto"
    ],
    "categories": [
      "quant-ph"
    ],
    "title": "A quantum-copying machine for equatorial qubits",
    "url": "https://arxiv.org/abs/quant-ph/0012033"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "92ab6535-24be-43d6-8e59-9667284175ec",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}