{
  "abstract": "Resonant atoms modify the electromagnetic environment that in turn determines their optical response, giving rise to a self-consistent light-matter problem at finite density. We investigate this feedback for the hydrogen Lyman- α transition using a local effective-medium description combined with an electromagnetic Green's function treatment of the atomic self-energy. Within the controlled regime, the self-consistent dressing produces a systematic density-dependent modification of the spectrum, including a shift of the spectral centroid and an asymmetric redistribution of integrated spectral weight. Comparison with a density expansion through fourth order provides an internal validity test: The local description remains quantitatively controlled up to approximately 2.0 × 10 21 m − 3 and becomes marginal above this density. Formal continuation to higher densities produces much stronger spectral restructuring, but this occurs together with the loss of perturbative and local-response control and is therefore not interpreted as a quantitative prediction of resolved high-density modes. To assess experimental relevance without assuming a microscopic hydrogen collision model, we additionally introduce a parametric collisional broadening Γ coll = n β . Collisional broadening becomes comparable to the controlled electromagnetic centroid shift for a characteristic coefficient of order 10 − 14 m 3 s − 1 . The robust prediction of the local theory is thus a density-dependent electromagnetic dressing of the resonant response, whereas its high-density breakdown identifies the regime in which a spatially resolved, nonlocal microscopic description of collective electromagnetic coupling becomes necessary.",
  "abstract_shown": true,
  "affiliations": [
    "University of Bergen"
  ],
  "article_type": "article",
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Johannes Fiedler",
      "orcid": "0000-0002-2179-0625"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f2brhbfrkahet.bib",
  "cited_by": 0,
  "doi": "10.1103/h6v7-fbqx",
  "fulltext_url": null,
  "id": "f2brhbfrkahet",
  "issns": [
    "2643-1564"
  ],
  "landing_url": "http://link.aps.org/doi/10.1103/h6v7-fbqx",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "feed-journal",
      "physics/general"
    ],
    [
      "openalex",
      "3107|Cold Atom Physics and Bose-Einstein Condensates"
    ]
  ],
  "openalex": "W7216083027",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-29",
  "publisher": "American Physical Society (APS)",
  "ris": "https://research.draconitic.com/paper/f2brhbfrkahet.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:18Z",
      "native_id": "10.1103/h6v7-fbqx",
      "source": "feed-aps",
      "url": "http://link.aps.org/doi/10.1103/h6v7-fbqx"
    },
    {
      "first_seen": "2026-10-30T12:17:55Z",
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      "url": "https://link.aps.org/doi/10.1103/h6v7-fbqx"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "openalex:3107|Cold Atom Physics and Bose-Einstein Condensates",
      "subfield": "amo"
    }
  ],
  "title": "Electromagnetic backaction in a resonant Bose gas: Controlled spectral shifts and limits of local response",
  "title_text": "Electromagnetic backaction in a resonant Bose gas: Controlled spectral shifts and limits of local response",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:33:17Z",
  "url": "https://research.draconitic.com/paper/f2brhbfrkahet",
  "venue": "Physical Review Research",
  "versions": []
}