{
  "abstract": "This paper presents a counterexample to the optimality conjecture for the trace distance based optimal state transformation problem proposed by Coutts et al. [Quantum 5, 448 (2021)]. The conjecture posits that for the trace distance based optimal state transformation problem, applying the sign function to the error matrix uniquely determines a dual certificate for every optimal solution. By constructing a counterexample in 2-dimensional Hilbert spaces, we disprove this conjecture.",
  "abstract_shown": true,
  "affiliations": [
    "School of Mathematical Sciences, University of Electronic Science and Technology of China",
    "State Key Laboratory of Mathematical Sciences, Academy of Mathematics and Systems Science, Chinese Academy of Sciences"
  ],
  "article_type": "Paper",
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Jianting Yang",
      "orcid": "0009-0000-2357-2114"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fv7wesfcyzteh.bib",
  "cited_by": 0,
  "doi": "10.22331/q-2026-10-28-2253",
  "fulltext_url": null,
  "id": "fv7wesfcyzteh",
  "issns": [
    "2521-327X"
  ],
  "landing_url": "https://quantum-journal.org/papers/q-2026-10-28-2253/",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "feed-journal",
      "physics/quantum"
    ],
    [
      "openalex",
      "1702|Quantum Information and Cryptography"
    ]
  ],
  "openalex": "W7117697265",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-28",
  "publisher": "Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften",
  "ris": "https://research.draconitic.com/paper/fv7wesfcyzteh.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:17Z",
      "native_id": "10.22331/q-2026-10-28-2253",
      "source": "feed-quantum",
      "url": "https://quantum-journal.org/papers/q-2026-10-28-2253/"
    },
    {
      "first_seen": "2026-10-30T12:17:58Z",
      "native_id": "10.22331/q-2026-10-28-2253",
      "source": "crossref",
      "url": "https://quantum-journal.org/papers/q-2026-10-28-2253/"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "feed-journal:physics/quantum",
      "subfield": "quantum"
    }
  ],
  "title": "A Counterexample to the Optimality Conjecture in Convex Quantum Channel Optimization",
  "title_text": "A Counterexample to the Optimality Conjecture in Convex Quantum Channel Optimization",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:17:58Z",
  "url": "https://research.draconitic.com/paper/fv7wesfcyzteh",
  "venue": "Quantum",
  "versions": []
}