{
  "abstract": "Randomized measurements provide state-independent readout for multiparameter quantum sensing. Although 3-designs retain a constant fraction of the quantum Fisher information (QFI) for every pure state, we show that 2-designs need not. In dimension \\(d\\), complete mutually unbiased bases (MUBs) retain exactly \\(1/(d+1)\\) of the QFI in the worst state and direction, attaining the universal lower bound for 2-designs built from orthonormal bases; symmetric informationally complete (SIC) measurements retain exactly \\((1-1/\\sqrt{d+1})/d\\). The loss comes from aligned blind spots. Relative to a basis, pure-state changes split into population and phase parts of equal dimension, but probabilities respond only to the former. Mutual unbiasedness turns a population change for one basis into a phase change for every other. The worst case already occurs for a qubit encoded in two levels. Independent random bases instead scatter their blind spots. In sufficiently large dimensions, five Haar-random bases retain, with high probability, a dimension-independent QFI fraction for every pure state and direction. Random Clifford measurements on any number of qubits retain exactly one third. Thus blind-spot geometry, not second-order symmetry alone, controls worst-case metrological performance.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.00599",
  "author_total": 2,
  "authors": [
    {
      "name": "Wanqing Li"
    },
    {
      "name": "Jiaxin Liu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1x76t5f4bd471.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.00599",
  "fulltext_url": null,
  "id": "1x76t5f4bd471",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.00599",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "quant-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2611.00599",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1x76t5f4bd471.ris",
  "sources": [
    {
      "first_seen": "2026-11-03T12:20:59Z",
      "native_id": "2611.00599",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.00599"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "The exact information cost of randomized measurements in quantum metrology",
  "title_text": "The exact information cost of randomized measurements in quantum metrology",
  "type": "preprint",
  "updated_at": "2026-11-05T15:20:18Z",
  "url": "https://research.draconitic.com/paper/1x76t5f4bd471",
  "venue": "arXiv",
  "versions": []
}