{
  "abstract": "We uncover a continuous phase transition in a quantum Hall ferromagnet (QHF) at filling factor $ν=1$, driven by vacuum fluctuations of a cavity. Our analysis starts with a Landau level projection in dipole gauge, where we find the states to be well-represented by a tensor product of the electronic and photonic degrees of freedom. Through analytic spin wave calculations, mean-field theory and density matrix renormalization group (DMRG) simulations, we show that for a spatially antisymmetric cavity field, the uniform QHF state is stable only for weak light-matter coupling and gives way to states of inhomogeneous electron density above a critical coupling. These states involve \"flanks\" of uniform QHF fluids, separated by a \"compact core\" of doubly occupied orbitals with the core size being the order parameter, which we dub as \"compact-core phases\". While the fully spin polarized electronic states are product states, entanglement builds up between the uniform QHF flanks across the compact core in the $S_z=0$ magnetic sector, motivating an ansatz for the compact-core electronic states. The transition boundary is exactly derived for product electronic states in terms of matter and cavity parameters, and numerically confirmed by DMRG. We also study the thin-cylinder limit near the critical point where quantum fluctuations are enhanced, and the many-body excited states in both phases by focusing on the entanglement spectrum degeneracies. Remarkably, the photon number is found to probe the order parameter of the transition, providing a possible experimental signature of the electronic transition and the compact-core states. Our study offers a rare example of a phase of electrons stabilized solely by coupling to the enhanced vacuum fluctuations of a cavity mode.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.14838",
  "author_total": 4,
  "authors": [
    {
      "name": "Ceren B. Dag"
    },
    {
      "name": "Luis Brey"
    },
    {
      "name": "Ganpathy Murthy"
    },
    {
      "name": "H. A. Fertig"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/6t6jscygpg5xk.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.14838",
  "fulltext_url": null,
  "id": "6t6jscygpg5xk",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.14838",
  "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",
      "cond-mat.mes-hall"
    ],
    [
      "arxiv",
      "cond-mat.str-el"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Strong Light-Matter Interactions"
    ]
  ],
  "openalex": "W7213354024",
  "pdf_url": "https://arxiv.org/pdf/2609.14838",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/6t6jscygpg5xk.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:25Z",
      "native_id": "2609.14838",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.14838"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mes-hall",
      "subfield": "condensed-matter"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Quantum Hall Ferromagnetism in a Cavity Vacuum",
  "title_text": "Quantum Hall Ferromagnetism in a Cavity Vacuum",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:25Z",
  "url": "https://research.draconitic.com/paper/6t6jscygpg5xk",
  "venue": "arXiv",
  "versions": []
}