{
  "abstract": "The decoder is a critical component of a fault-tolerant quantum computer, computing corrections based on parity-check measurements performed throughout the computation. A soft decoder supplements its output with a confidence score which, when used alongside post-selection, can substantially improve logical performance. We introduce a soft beam search decoder for quantum low-density parity-check codes that uses internal decoder data as a confidence metric, removing the need for extra computation. We perform circuit-level simulations of five quantum LDPC codes relevant for superconducting and trapped ion architectures equipped with our global soft decoder and we obtain up to $580\\times$ logical-error suppression at a physical error rate of $10^{-3}$ while rejecting only $0.1\\%$ of shots. Then, we simulate an error detected measurement, which is a core logical operation of the walking cat architecture, using a streaming version of soft beam decoder and we achieve up to $210\\times$ error suppression while increasing the rejection probability by only $0.5$ percentage points. Finally, we revisit recent quantum LDPC code memory experiments on trapped ions, demonstrating that our soft decoder doubles the logical qubit lifetimes at the price of a mean rejection rate of $2.6\\%$--$5.6\\%$ per syndrome round, bringing all five codes into the beyond-breakeven regime.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.26958",
  "author_total": 4,
  "authors": [
    {
      "name": "Arda Aydin"
    },
    {
      "name": "Edwin Tham"
    },
    {
      "name": "Nicolas Delfosse"
    },
    {
      "name": "Min Ye"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7jrqw52kth6v4.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.26958",
  "fulltext_url": null,
  "id": "7jrqw52kth6v4",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.26958",
  "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",
      "1702|Quantum Computing Algorithms and Architecture"
    ]
  ],
  "openalex": "W7214201704",
  "pdf_url": "https://arxiv.org/pdf/2609.26958",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7jrqw52kth6v4.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:56Z",
      "native_id": "2609.26958",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.26958"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Soft decoding for quantum LDPC codes with experimental validation",
  "title_text": "Soft decoding for quantum LDPC codes with experimental validation",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:56Z",
  "url": "https://research.draconitic.com/paper/7jrqw52kth6v4",
  "venue": "arXiv",
  "versions": []
}