{
  "annotation_id": "2e5cdb12-53cc-41f9-8fd7-d3b73990f6aa",
  "date_created": "2026-03-02T18:02:16.551000Z",
  "date_modified": "2026-03-02T18:02:16.551000Z",
  "file_hash": "e10534cffc73cb48cecbfce8b8476e6cc7ffa5ef2adbe18e50be3bb7ef76906f",
  "private": false,
  "record": {
    "abstract": "We derive the optimal input states and the optimal quantum measurements for\nestimating the unitary action of a given symmetry group, showing how the\noptimal performance is obtained with a suitable use of entanglement. Optimality\nis defined in a Bayesian sense, as minimization of the average value of a given\ncost function. We introduce a class of cost functions that generalizes the\nHolevo class for phase estimation, and show that for states of the optimal form\nall functions in such a class lead to the same optimal measurement. A first\napplication of the main result is the complete proof of the optimal efficiency\nin the transmission of a Cartesian reference frame. As a second application, we\nderive the optimal estimation of a completely unknown two-qubit maximally\nentangled state, provided that N copies of the state are available. In the\nlimit of large N, the fidelity of the optimal estimation is shown to be\n1-3/(4N).",
    "arxiv_id": "quant-ph/0506267",
    "authors": [
      "G. Chiribella",
      "G. M. D\u0027Ariano",
      "M. F. Sacchi"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.72.042338",
    "journal_ref": "Phys. Rev. A 72 042338 (2005)",
    "title": "Optimal estimation of group transformations using entanglement",
    "url": "https://arxiv.org/abs/quant-ph/0506267"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "9f8ce524-8747-4f6a-a181-077e90d8a1ef",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}