{
  "annotation_id": "d1d6ea77-fbde-49e2-91d1-03e768aa1c12",
  "date_created": "2026-03-02T18:02:30.848000Z",
  "date_modified": "2026-03-02T18:02:30.848000Z",
  "file_hash": "801421c0bc6b9b420fa636b6c8ee349e889588828899b357b4ba04822e798331",
  "private": false,
  "record": {
    "abstract": "The estimation of the density matrix of a $k$-level quantum system is studied\nwhen the parametrization is given by the real and imaginary part of the entries\nand they are estimated by independent measurements. It is established that the\nproperties of the estimation procedure depend very much on the invertibility of\nthe true state. In particular, in case of a pure state the estimation is less\nefficient. Moreover, several estimation schemes are compared for the unknown\nstate of a qubit when one copy is measured at a time. It is shown that the\naverage mean quadratic error matrix is the smallest if the applied observables\nare complementary. The results are illustrated by computer simulations.",
    "arxiv_id": "quant-ph/0610124",
    "authors": [
      "D. Petz",
      "K. M. Hangos",
      "A. Magyar"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1088/1751-8113/40/28/S06",
    "title": "Point Estimation of States of Finite Quantum Systems",
    "url": "https://arxiv.org/abs/quant-ph/0610124"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "e89e2f09-8eaa-4038-bb5b-a729f5f04580",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}