{
  "abstract": "A key appeal of quantum low-density parity check (qLDPC) codes is their ability to suppress stochastic Pauli noise below nonzero thresholds. Coherent errors are fundamentally different: they produce superpositions of error patterns whose amplitudes can interfere even after syndrome measurement. Rigorous understanding of coherent errors remains limited. Here we show that general qLDPC codes admit a nonzero code capacity threshold against local coherent noise and more generally local channel noise. For any family of qLDPC codes with distance $d=Ω(\\log n)$, we show that there is a constant noise strength below which the logical recovery error in diamond distance decays exponentially with the code distance. The result is established for optimal recovery as well as the minimum-weight decoder. The key technical ingredient is what we call a \\emph{cluster resummation}: rather than bounding superposed error configurations one by one, we isolate a large connected error cluster in the channel expansion and exactly resum all errors disconnected from it before taking norms. Standard cluster counting then yields exponential suppression. This work resolves a longstanding challenge in fault tolerance theory, providing general robustness guarantees for qLDPC codes against coherent noise and laying a rigorous foundation for future studies of fault-tolerant quantum technologies.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.20537",
  "author_total": 5,
  "authors": [
    {
      "name": "Zhengyi Han"
    },
    {
      "name": "Yuanchen Zhao"
    },
    {
      "name": "Yijia Xu"
    },
    {
      "name": "Yixu Wang"
    },
    {
      "name": "Zi-Wen Liu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/729smd0ws9a48.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.20537",
  "fulltext_url": null,
  "id": "729smd0ws9a48",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.20537",
  "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",
      "1702|Quantum Computing Algorithms and Architecture"
    ]
  ],
  "openalex": "W7213583747",
  "pdf_url": "https://arxiv.org/pdf/2609.20537",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/729smd0ws9a48.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:19Z",
      "native_id": "2609.20537",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.20537"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Coherent error threshold for quantum LDPC codes",
  "title_text": "Coherent error threshold for quantum LDPC codes",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:19Z",
  "url": "https://research.draconitic.com/paper/729smd0ws9a48",
  "venue": "arXiv",
  "versions": []
}