{
  "annotation_id": "1d24ab01-a6d6-4832-b60e-aeef392c295c",
  "date_created": "2026-03-02T18:01:42.413000Z",
  "date_modified": "2026-03-02T18:01:42.413000Z",
  "file_hash": "5f44c476a47902e0fec5fc26c4a9a623f72e68733c43bdc2f25579ca453587e9",
  "private": false,
  "record": {
    "abstract": "For a system of N spins 1/2 there are quantum states that can encode a\ndirection in an intrinsic way. Information on this direction can later be\ndecoded by means of a quantum measurement. We present here the optimal encoding\nand decoding procedure using the fidelity as a figure of merit. We compute the\nmaximal fidelity and prove that it is directly related to the largest zeroes of\nthe Legendre and Jacobi polynomials. We show that this maximal fidelity\napproaches unity quadratically in 1/N. We also discuss this result in terms of\nthe dimension of the encoding Hilbert space.",
    "arxiv_id": "quant-ph/0012006",
    "authors": [
      "E. Bagan",
      "M. Baig",
      "A. Brey",
      "R. Munoz-Tapia",
      "R. Tarrach"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.63.052309",
    "journal_ref": "Phys. Rev. A63, 052309 (2001)",
    "title": "Optimal encoding and decoding of a spin direction",
    "url": "https://arxiv.org/abs/quant-ph/0012006"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "56f1f5f9-dba5-4a2c-8e11-5266243ea320",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}