{
  "annotation_id": "5b960025-5213-4a11-a3f0-53592229a7a6",
  "date_created": "2026-03-02T18:01:59.818000Z",
  "date_modified": "2026-03-02T18:01:59.818000Z",
  "file_hash": "1b69c79c9985b77360203b29fac8f5f967e001171fd1db9fcddabaad3ae3fdcc",
  "private": false,
  "record": {
    "abstract": "The problem of optimally estimating an unknown unitary quantum operation with\nthe aid of entanglement is addressed. The idea is to prepare an entangled pair,\napply the unknown unitary to one of the two parts and then measure the joint\noutput state. This measurement could be an entangled one or it could be\nseparable (e.g., LOCC). A comparison is made between these possibilities and it\nis shown that by using non-separable measurements one can improve the accuracy\nof the estimation by a factor of $2(d+1)/d$ where $d$ is the dimension of the\nHilbert space on which $U$ acts.",
    "arxiv_id": "quant-ph/0305104",
    "authors": [
      "Manuel A. Ballester"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.69.022303",
    "journal_ref": "Phys. Rev. A 69, 022303 (2004)",
    "title": "Estimation of unitary quantum operations",
    "url": "https://arxiv.org/abs/quant-ph/0305104"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "a3385486-e808-4b05-ad46-391f04c9294f",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}