{
  "abstract": "The Scharnhorst effect in quantum electrodynamics predicts a superluminal velocity shift $δc>0$ at low photon frequencies due to vacuum fluctuations between two mirrors. Although theoretically robust (no causality violation), the effect is extraordinarily small ($δc/c\\approx 10^{-32}$ for mirrors $1\\,μ{\\rm m}$ apart) and outside current experimental reach. Here we propose a condensed matter analogue, replacing the photons in the electromagnetic vacuum by phonon excitations of a Bose-Einstein condensate. In an idealized geometry, the two-dimensional surface of a cylinder (circumference $L$) at zero temperature, the axial speed of sound is increased due to zero-point fluctuations of the condensate by $δc/c\\simeq 5\\times 10^{-3}\\,\\tilde{g}$ at $L\\simeq 2\\,ξ$, to first order in the dimensionless interaction constant $\\tilde{g}\\simeq 10^{-1}$ of the Bose gas of healing length $ξ\\simeq 1\\,μ{\\rm m}$. This is 28 orders of magnitude larger than the photonic effect, basically because phonons have a self-interaction while photons only interact via massive electrons. We discuss the prospects for observation of the acoustic Scharnhorst effect, the main restriction being the low-temperature requirement.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.14155",
  "author_total": 1,
  "authors": [
    {
      "name": "C. W. J. Beenakker"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1nhajn90jkgzr.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.14155",
  "fulltext_url": null,
  "id": "1nhajn90jkgzr",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.14155",
  "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",
      "cond-mat.quant-gas"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Quantum Electrodynamics and Casimir Effect"
    ]
  ],
  "openalex": "W7213223891",
  "pdf_url": "https://arxiv.org/pdf/2609.14155",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-12",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1nhajn90jkgzr.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:25Z",
      "native_id": "2609.14155",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.14155"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.quant-gas",
      "subfield": "amo"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.quant-gas",
      "subfield": "condensed-matter"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Phonon Scharnhorst effect: Acoustic analogue of the vacuum-fluctuation-boosted speed of light",
  "title_text": "Phonon Scharnhorst effect: Acoustic analogue of the vacuum-fluctuation-boosted speed of light",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:25Z",
  "url": "https://research.draconitic.com/paper/1nhajn90jkgzr",
  "venue": "arXiv",
  "versions": []
}