{
  "abstract": "Systems characterized by an energy gap between the ground state and excited states support a growing number of thermal excitations upon raising the temperature. Provided these excitations interact with each other, their number affects the size of the energy gap akin to a harmonic oscillator where the oscillation frequency is damping dependent. Here we show that once a critical number of excitations is reached, the excitation population becomes thermodynamically unstable and the system transitions between two states. This transition is marked by a divergence in the specific heat, which does not have to be accompanied by an order parameter, nor by the full closure of the gap. We illustrate the thermodynamics using a simple two level system and superfluid $^4$He as examples, and we argue that the hidden order transition in URu$_2$Si$_2$ is an example of such an occupancy driven transition in the absence of an order parameter.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.31564",
  "author_total": 3,
  "authors": [
    {
      "name": "Ian Madden"
    },
    {
      "name": "Alex Kociubinski"
    },
    {
      "name": "Wouter Montfrooij"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7wxbq7hqaktf0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.31564",
  "fulltext_url": null,
  "id": "7wxbq7hqaktf0",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.31564",
  "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.other"
    ],
    [
      "arxiv",
      "cond-mat.quant-gas"
    ],
    [
      "arxiv",
      "cond-mat.str-el"
    ],
    [
      "openalex",
      "3104|Rare-earth and actinide compounds"
    ]
  ],
  "openalex": "W7223366725",
  "pdf_url": "https://arxiv.org/pdf/2610.31564",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7wxbq7hqaktf0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.31564",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.31564"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.quant-gas",
      "subfield": "amo"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.other",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Occupancy Driven Phase Transitions in Gapped Systems",
  "title_text": "Occupancy Driven Phase Transitions in Gapped Systems",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/7wxbq7hqaktf0",
  "venue": "arXiv",
  "versions": []
}