{
  "abstract": "For unknown three-qubit pure states, we characterize the optimal trade-off among GHZ-class certification, binary probability readout of the three-tangle, and conditional state retention. The vanishing ideal of the null class specifies the optimal certification subspace, while a polynomial multiplication operator gives the spectral limit for binary readout. Four copies are necessary for a nonzero certificate. A fifth copy raises the optimal success probability from $τ^{2}/48$ to $5τ^{2}/72$ and permits the original unknown state to be retained, where $τ$ is the three-tangle. We obtain this gain as an instance of a general symmetry-based additional-copy theorem. At six copies the optimal certification probability is $(39+2S)τ^{2}/296$, with $S=\\sum_{X}\\mathrm{Tr}\\,ρ_{X}^{2}$, whereas the largest exact binary probability is $τ^{2}/8$. Local Schur measurements and conditional local operations with classical communication attain these bounds. Retaining the full six-copy branch record yields a weighted estimator with lower variance than binary thinning of the same data. Explicit circuits and fixed-budget comparisons connect the success probabilities to input-copy consumption, retained quantum output, and coherent gate cost.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.08233",
  "author_total": 5,
  "authors": [
    {
      "name": "Yu-Xin Wu"
    },
    {
      "name": "Yuan-Hong Tao"
    },
    {
      "name": "Ji-Hui Mo"
    },
    {
      "name": "Peng-Fei Ma"
    },
    {
      "name": "Shu-Hui Wu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/abw8047tc6fkq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.08233",
  "fulltext_url": null,
  "id": "abw8047tc6fkq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.08233",
  "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": null,
  "pdf_url": "https://arxiv.org/pdf/2611.08233",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-05",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/abw8047tc6fkq.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T18:21:30Z",
      "native_id": "2611.08233",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.08233"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Optimal finite-copy readout of three-qubit entanglement with state retention",
  "title_text": "Optimal finite-copy readout of three-qubit entanglement with state retention",
  "type": "preprint",
  "updated_at": "2026-11-09T00:20:41Z",
  "url": "https://research.draconitic.com/paper/abw8047tc6fkq",
  "venue": "arXiv",
  "versions": []
}