{
  "abstract": "Eve receives genuine average photon counts from two opaque devices, finds input-independent single-party report distributions, and sees little activity in a specified leakage monitor. Do these observations establish physical isolation? We construct a cavity-based counterexample. Independently operated controls activate a shared interaction after the inputs arrive. Internal block measurements yield a CHSH score $S=13/4$ for four repetitions, approaching $4$ for large blocks. A fresh shared random bit symmetrizes the binary results without changing their parity; local preparation of vacuum or one-photon output states then produces truthful photon-number reports with exactly non-signalling marginals. A dispersive-bus model also permits weak monitored leakage; an illustrative dissipative calculation gives $S\\simeq3.1702$ with ideal output encoding. These scores exceed $2\\sqrt2$ because the devices interact during their response, not because quantum mechanics is violated. The construction separates honest measurement, non-signalling reported statistics, and causal isolation, while making the additional randomness, preparation, and monitoring assumptions explicit.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.09103",
  "author_total": 1,
  "authors": [
    {
      "name": "Yueying Wu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bxfspjzw8en84.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.09103",
  "fulltext_url": null,
  "id": "bxfspjzw8en84",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.09103",
  "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": "W7220923581",
  "pdf_url": "https://arxiv.org/pdf/2610.09103",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bxfspjzw8en84.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:35:35Z",
      "native_id": "2610.09103",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.09103"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "The coupler Eve did not monitor: non-signalling reports from interacting cavities",
  "title_text": "The coupler Eve did not monitor: non-signalling reports from interacting cavities",
  "type": "preprint",
  "updated_at": "2026-10-30T12:35:35Z",
  "url": "https://research.draconitic.com/paper/bxfspjzw8en84",
  "venue": "arXiv",
  "versions": []
}