{
  "annotation_id": "c01b3751-e154-4bc2-b83c-ef8b0021dd9a",
  "date_created": "2026-03-02T18:01:59.348000Z",
  "date_modified": "2026-03-02T18:01:59.348000Z",
  "file_hash": "0436d9e82a22e677c1b57294fbaa1f167652e940e80bedcf7b82bfbec2fa08f9",
  "private": false,
  "record": {
    "abstract": "The study of quantum cryptography and quantum entanglement has traditionally\nbeen based on two-level quantum systems (qubits) and more recently on\nthree-level systems (qutrits). We investigate several classes of\nstate-dependent quantum cloners for four-level systems (quartits). These\nresults apply to symmetric as well as asymmetric cloners, so that the balance\nbetween the fidelity of the two clones can also be analyzed. We extend Cerf\u0027s\nformalism for cloning states in order to derive cloning machines that remain\ninvariant under certain unitary transformations. Our results show that a\ndifferent cloner has to be used for two mutually unbiased bases which are\nrelated by a double Hadamard transformation, than for two mutually unbiased\nbases that are related by a Fourier transformation. This different cloner is\nobtained thanks to a redefinition of Bell states that respects the intrinsic\nsymmetries of the Hadamard transformation.",
    "arxiv_id": "quant-ph/0304149",
    "authors": [
      "Thomas Durt",
      "Bob Nagler"
    ],
    "categories": [
      "quant-ph"
    ],
    "title": "About Covariant Quartit Cloning Machines",
    "url": "https://arxiv.org/abs/quant-ph/0304149"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "638d10e4-0799-4c39-a6cf-860e5f234783",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}