{
  "abstract": "Device-independent quantum key distribution (DIQKD) can guarantee security without trusting the internal workings of the measurement devices, but extending it to fiber networks demands high-quality entanglement, reliable heralding, and faithful photon transmission simultaneously. Here, we address these requirements in an event-ready asymmetric atom-photon architecture implemented over $25\\,\\mathrm{km}$ of spooled telecom fiber. A single trapped $^{40}\\mathrm{Ca}^{+}$ ion forms one party of the protocol while a single transmitted photon measured at the remote station forms the other. Double quantum frequency conversion and active polarization stabilization preserve the atom-photon quantum correlation across the full link. We obtain a Clauser-Horne-Shimony-Holt parameter of $|S|=2.75^{+0.16}_{-0.15}$, exceeding the threshold $|S|=2.362$ required for a positive asymptotic secret-key fraction under the DIQKD model used. Within the same asymptotic model, this corresponds to a conservative estimate of 69 secret-key bits out of 10908 detected Bell states. The demonstrated architecture establishes a route towards DIQKD in heterogeneous, repeater-compatible quantum networks.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.25795",
  "author_total": 7,
  "authors": [
    {
      "name": "Jonas Meiers"
    },
    {
      "name": "Christian Haen"
    },
    {
      "name": "Max Bergerhoff"
    },
    {
      "name": "Pascal Baumgart"
    },
    {
      "name": "Tobias Bauer"
    },
    {
      "name": "Christoph Becher"
    },
    {
      "name": "Jürgen Eschner"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f49h6rg08rhv1.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.25795",
  "fulltext_url": null,
  "id": "f49h6rg08rhv1",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.25795",
  "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 Information and Cryptography"
    ]
  ],
  "openalex": "W7214077848",
  "pdf_url": "https://arxiv.org/pdf/2609.25795",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/f49h6rg08rhv1.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:56Z",
      "native_id": "2609.25795",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.25795"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "An asymmetric atom-photon architecture for device-independent quantum key distribution over 25 km",
  "title_text": "An asymmetric atom-photon architecture for device-independent quantum key distribution over 25 km",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:56Z",
  "url": "https://research.draconitic.com/paper/f49h6rg08rhv1",
  "venue": "arXiv",
  "versions": []
}