{
  "annotation_id": "e8a96fbf-e50d-4f23-a669-6923d21ddd68",
  "date_created": "2026-03-02T18:01:38.732000Z",
  "date_modified": "2026-03-02T18:01:38.732000Z",
  "file_hash": "5ee0ceb9de09ea6275b2ed3dfae9c2841a99a331484623da2a997aa213b2eb40",
  "private": false,
  "record": {
    "abstract": "We address the \"major open problem\" of evaluating how much increased\nefficiency in estimation is possible using non-separable, as opposed to\nseparable, measurements of N copies of m-level quantum systems. First, we study\nthe six cases m = 2, N = 2,...,7 by computing the the 3 x 3 Fisher information\nmatrices for the corresponding optimal measurements recently devised by Vidal\net al (quant-ph/9812068) for N = 2,...,7. We obtain simple polynomial\nexpressions for the (\"Gill-Massar\") traces of the products of the inverse of\nthe quantum Helstrom information matrix and these Fisher information matrices.\nThe six traces all have minima of 2 N -1 in the pure state limit, while for\nseparable measurements (quant-ph/9902063), the traces can equal N, but not\nexceed it. Then, the result of an analysis for m = 3, N = 2 leads us to\nconjecture that for optimal measurements for all m and N, the \"Gill-Massar\ntrace\" achieves a minimum of (2N-1)(m-1) in the pure state limit.",
    "arxiv_id": "quant-ph/0006009",
    "authors": [
      "Paul B. Slater"
    ],
    "categories": [
      "quant-ph",
      "physics.data-an"
    ],
    "doi": "10.1088/0305-4470/34/35/328",
    "journal_ref": "J. Phys. A. 34 (7 Sept 2001) 7029-7046",
    "title": "Increased Efficiency of Quantum State Estimation Using Non-Separable   Measurements",
    "url": "https://arxiv.org/abs/quant-ph/0006009"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "741e1f52-7a03-431e-b5d5-15d2b9bceac2",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}