{
  "abstract": "We examine the conditions under which quantum parameter estimation is compatible with the concept of a ``true'' quantity value: a unique value of the estimated quantity that exists prior to and independently of measurement. While quantum parameter estimation typically assumes that the quantity to be estimated is a parameter, we argue that this assumption can be lifted, opening the way to a more general formulation of estimation that may apply even in situations where the quantity to be estimated is no longer a parameter, but instead a quantum variable susceptible to quantum fluctuations. We identify three assumptions that characterize the way estimation is often presented in the quantum metrology literature, namely, as a procedure for inferring an unknown ``true value\", which is assumed to be unique and to exist prior to and independently of measurement. Using our more general framework, we prove a no-go theorem showing that the preceding assumptions are jointly incompatible with two further assumptions: the completeness of the quantum state (no `hidden variables'), and the presence of entanglement between the probe systems and the system under measurement. We note that the presence of such entanglement is a generic prediction of standard quantum theory. Consequently, if one is not willing to accept hidden variables, nor willing to modify standard quantum theory by introducing a new physical mechanism that destroys entanglement at some scale or regime, then a realist account of estimation is ultimately impossible.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.31632",
  "author_total": 3,
  "authors": [
    {
      "name": "Jacques L. Pienaar"
    },
    {
      "name": "Eran Tal"
    },
    {
      "name": "Asya Ciftci"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/2zrhr8kzzvarm.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.31632",
  "fulltext_url": null,
  "id": "2zrhr8kzzvarm",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.31632",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Quantum Mechanics and Applications"
    ]
  ],
  "openalex": "W7223394653",
  "pdf_url": "https://arxiv.org/pdf/2610.31632",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/2zrhr8kzzvarm.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.31632",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.31632"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "What does quantum parameter estimation estimate? A no-go result for true quantity values",
  "title_text": "What does quantum parameter estimation estimate? A no-go result for true quantity values",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/2zrhr8kzzvarm",
  "venue": "arXiv",
  "versions": []
}