{
  "abstract": "We show that an $N$-site quantum Rabi ring with matched giant-atom couplings has $2^N$ degenerate superradiant configurations as the atomic-to-cavity frequency ratio $η=Δ/ω$ tends to infinity. Each atom couples to two cavities two sites apart, and the photon hopping carries a phase $π/2$. Tuning the ratio of contact strengths to the photon hopping reduces the mean-field energy to a sum of single-site Rabi energies, with a common critical coupling for all momentum-pair sectors. The degeneracy survives quadratic quantum fluctuations despite a dispersive excitation spectrum. At finite $η$, second-order processes involving the local cubic anharmonicity generate a same-sublattice Ising coupling of order $ω/η$, selecting ferro- and antiferro-superradiant configurations. This quantum order-by-disorder effect has no classical counterpart. Four-site calculations retaining all spin states quantitatively support the predicted energy coefficients. The separation between the induced coupling and the excitation gap allows a broad temperature interval with macroscopic photon occupation and short-range correlations between displacement signs.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.09880",
  "author_total": 2,
  "authors": [
    {
      "name": "Shu He"
    },
    {
      "name": "Li-Wei Duan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bpskdezcjyk12.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.09880",
  "fulltext_url": null,
  "id": "bpskdezcjyk12",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.09880",
  "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",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Strong Light-Matter Interactions"
    ]
  ],
  "openalex": "W7220978882",
  "pdf_url": "https://arxiv.org/pdf/2610.09880",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-07",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bpskdezcjyk12.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:37Z",
      "native_id": "2610.09880",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.09880"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Extensively degenerate superradiant phase in a giant-atom quantum Rabi ring",
  "title_text": "Extensively degenerate superradiant phase in a giant-atom quantum Rabi ring",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:37Z",
  "url": "https://research.draconitic.com/paper/bpskdezcjyk12",
  "venue": "arXiv",
  "versions": []
}