{
  "abstract": "Server-aided Bell-state networks with sequential local encoding are an established approach to mediated key distribution. Against this background, we study a Loop-Back architecture in which two source-free, detector-free users transform the same traveling qubit. Alice privately samples $r\\in\\mathbb{Z}*2^2$, prepares $|β_r\\rangle$ over the complete Bell basis, retains one qubit, and uses $r$ as the reference for the returned pair. A deterministic Pauli-composition mode, $U*{\\mathrm{eff}}=U_2U_1$, serves as a reference to prior serial-unitary protocols. The main extension instead uses the two same-axis settings $R(\\pmα)$ and a reference-versus-complement Bell test. Opposite rotations cancel, whereas equal rotations add, so $P(C\\mid\\mathrm{disagreement})=0$ and $P(C\\mid\\mathrm{agreement})=\\sin^2(2α)$. At $α=π/8$, agreement is certified with probability $1/2$, and the overall conclusive-key probability is $1/4$ for unbiased choices. The same event supplies one shared raw-key bit. For the Pauli mode, a one-qubit Pauli twirl hides either user's factor from an endpoint mediator that may prepare an arbitrary qubit--ancilla state and choose the final measurement, provided the other Pauli is uniform and the traveler is inaccessible between users. The rotational guarantee is narrower: common-sign privacy holds only for the prescribed Bell source and coarse-grained instrument. A polarization implementation can normalize the private reference to the singlet and use a beam splitter with verified two-photon detection; loss produces a third, discarded outcome. The proposal is theoretical and does not claim composable security or experimental validation.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Optical Switching and Networking, 62 (2026) 100892",
  "arxiv": "2606.19551",
  "author_total": 1,
  "authors": [
    {
      "name": "Luis Adrián Lizama-Pérez"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/39dk1fqxhzd0t.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2606.19551",
  "fulltext_url": null,
  "id": "39dk1fqxhzd0t",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2606.19551",
  "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.CR"
    ],
    [
      "arxiv",
      "quant-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2606.19551",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/39dk1fqxhzd0t.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2606.19551",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2606.19551"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Rotational Bell-State Loop-Back Key Establishment and Agreement Certification for Passive Users",
  "title_text": "Rotational Bell-State Loop-Back Key Establishment and Agreement Certification for Passive Users",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/39dk1fqxhzd0t",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1016/j.osn.2026.100892",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}