{
  "abstract": "This work develops an effective channel model for distributed passive-user Loop-Back quantum key distribution. In the intended key-establishment setting, the two passive users \\(B_1\\) and \\(B_2\\) are the legitimate lightweight parties that establish a shared secret key by using Alice as an active quantum preparation-and-measurement infrastructure. A single active station prepares and measures BB84 states, while two remote users apply only local polarization rotations. We show that the passive-user pair can be externally encapsulated as an effective Loop-Back node whose observable action is a balanced mixture of conjugate-basis dephasings, equivalently represented as an anisotropic Pauli channel with identity, \\(X\\), and \\(Z\\) components and no \\(Y\\) component. This structure differs from isotropic depolarization and recovers the ideal conclusive-event probability \\(P_{\\mathrm{conc}}=1/4\\). The model also clarifies why non-orthogonal intermediate states are necessary for passive-user security. This channel-level description characterizes Alice's observable statistics and provides a compact basis for subsequent analysis of passive-user Loop-Back QKD under realistic optical and adversarial conditions.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Optical and Quantum Electronics 58, 587 (2026)",
  "arxiv": "2606.04247",
  "author_total": 1,
  "authors": [
    {
      "name": "Luis Adrián Lizama-Pérez"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3akbw9jk501k7.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2606.04247",
  "fulltext_url": null,
  "id": "3akbw9jk501k7",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2606.04247",
  "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",
      "cs.IT"
    ],
    [
      "arxiv",
      "math.IT"
    ],
    [
      "openalex",
      "1702|Quantum Information and Cryptography"
    ]
  ],
  "openalex": "W7163588903",
  "pdf_url": "https://arxiv.org/pdf/2606.04247",
  "pmcid": null,
  "pmid": null,
  "published": "2026-06-02",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3akbw9jk501k7.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:40Z",
      "native_id": "2606.04247",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2606.04247"
    }
  ],
  "subjects": [
    {
      "field": "mathematics",
      "origin": "arxiv:math.IT",
      "subfield": "general"
    }
  ],
  "title": "An Effective Pauli-Channel Model for Passive-User Loop-Back QKD",
  "title_text": "An Effective Pauli-Channel Model for Passive-User Loop-Back QKD",
  "type": "preprint",
  "updated_at": "2026-11-05T15:20:28Z",
  "url": "https://research.draconitic.com/paper/3akbw9jk501k7",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1016/j.osn.2026.100892",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}