{
  "abstract": "Discrete-Modulated (DM) Continuous-Variable (CV) Quantum Key Distribution (QKD) is an experimentally attractive approach to quantum cryptography, offering high key rates over metropolitan-scale distances while relying on state-of-the-art telecom infrastructure. However, a fundamental gap has remained between this experimental promise and rigorous security: for more than two decades, DM CV-QKD has lacked a complete composable finite-size security proof against coherent attacks. Existing works either restrict the adversary to collective attacks, impose additional finite-dimensional assumptions, apply only to specific modulation formats, or fail to recover the known asymptotic rates. Here, we resolve this longstanding problem by establishing the first complete composable finite-size security proof for DM CV-QKD protocols against coherent attacks, incorporating imperfect detectors and both fixed- and variable-length protocol variants. Our proof introduces two central results of broader interest: an infinite-dimensional marginal-constrained entropy accumulation theorem (iMEAT) and a rigorous dimension-reduction technique that makes the infinite-dimensional security bounds numerically tractable. The resulting key rates recover the known asymptotic rates and outperform established finite-size bounds based on collective attacks, while yielding positive key rates beyond $70$km for experimentally relevant block sizes and parameters. Thus, our work closes a longstanding gap and places an experimentally attractive class of CV-QKD protocols on a rigorous composable security footing and provides a pathway towards their practical deployment.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.16105",
  "author_total": 4,
  "authors": [
    {
      "name": "Lars Kamin"
    },
    {
      "name": "Ian George"
    },
    {
      "name": "John Burniston"
    },
    {
      "name": "Florian Kanitschar"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/89fb26gdt1spw.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.16105",
  "fulltext_url": null,
  "id": "89fb26gdt1spw",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.16105",
  "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 Information and Cryptography"
    ]
  ],
  "openalex": "W7213396513",
  "pdf_url": "https://arxiv.org/pdf/2609.16105",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-25",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/89fb26gdt1spw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2609.16105",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.16105"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Unconditional Security of Discrete-Modulated CV-QKD from Infinite-Dimensional MEAT",
  "title_text": "Unconditional Security of Discrete-Modulated CV-QKD from Infinite-Dimensional MEAT",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:35Z",
  "url": "https://research.draconitic.com/paper/89fb26gdt1spw",
  "venue": "arXiv",
  "versions": []
}