{
  "abstract": "In a commercial entanglement-distribution system over telecom fibre, the single-photon detectors are the largest part of the hardware cost. In entanglement-based quantum key distribution (QKD), both photons of each pair must be detected. With two telecom photons, each arm needs either an InGaAs single-photon avalanche diode (SPAD) of low efficiency or a superconducting nanowire single-photon detector (SNSPD) with its own cryostat. We study a highly nondegenerate photon-pair source that needs a telecom detector on one arm only. Two periodically poled KTiOPO$_4$ (ppKTP) crystals pumped at 405~nm emit pairs at 548 and 1550~nm. A Si-SPAD with 82\\% efficiency detects the 548~nm photon at the source node, and only the 1550~nm photon travels through fibre. A first, unoptimised module in a polarisation-correlated configuration generates about $1.5\\times10^6$ pairs/s per mW of pump power. It collects 13\\% of the pairs on the 548~nm arm and 23\\% on the 1550~nm arm. In an asymptotic BBM92 model, we compare its links with generic $2\\times1550$~nm links that use a bright published source at the same pump power. At 50~km, our link with one SNSPD costs about 25\\% more per secret bit than the generic link with one SNSPD. With optimistic target values of 52\\% collection and twice the brightness, it costs about 40\\% as much as the generic link with two SNSPDs. Our link without a cryostat then costs about 70\\% less than the generic link with one SNSPD. If every link runs at its own best pump power, the two-SNSPD link is again the cheapest. The source can also serve clock synchronisation and detector calibration, which need only time-correlated pairs. All key rates assume the entangled configuration of the source, which is under development.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.41709",
  "author_total": 7,
  "authors": [
    {
      "name": "Sander van Haagen"
    },
    {
      "name": "Bora Ulu"
    },
    {
      "name": "Alper Ozulker"
    },
    {
      "name": "Wardah Mahmood"
    },
    {
      "name": "Michal Krelina"
    },
    {
      "name": "Utku Tefek"
    },
    {
      "name": "Kadir Durak"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0jb4ynnne8nsh.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.41709",
  "fulltext_url": null,
  "id": "0jb4ynnne8nsh",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.41709",
  "language": null,
  "licence": "CC-BY-NC-SA-4.0",
  "licence_label": "CC BY-NC-SA 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-sa/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "quant-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.41709",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0jb4ynnne8nsh.ris",
  "sources": [
    {
      "first_seen": "2026-11-02T12:21:15Z",
      "native_id": "2610.41709",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.41709"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "A Highly Nondegenerate Photon-Pair Source for Detector-Matched Quantum Key Distribution",
  "title_text": "A Highly Nondegenerate Photon-Pair Source for Detector-Matched Quantum Key Distribution",
  "type": "preprint",
  "updated_at": "2026-11-04T15:20:51Z",
  "url": "https://research.draconitic.com/paper/0jb4ynnne8nsh",
  "venue": "arXiv",
  "versions": []
}