{
  "abstract": "We consider two quantum spin models on $k$-partite graphs. The system is assumed to be invariant under all permutations within any of the $k$ sets. In the limit of infinitely many particles, the Gibbs state is described as a mixture of independent spins due to a version of the Quantum de Finetti theorem. First, we study a spin-1/2 antiferromagnetic Heisenberg model and identify its three phases. At low temperature all $k$ sets are magnetised but cancel each other, at medium temperature there is a net magnetic field and at high temperature there is no magnetisation. The magnetisation temperature is a solution to a $k$-degree polynomial. Second, we allow a general spin $s$ and identify all orthogonally invariant models which have frustration. The criterium for a frustration-free model is that the $k$-sets can be partitioned into two parts, where the only antiferromagnetic interaction is between the two parts.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.12873",
  "author_total": 1,
  "authors": [
    {
      "name": "Oskar Olander"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/754s104z6zrbg.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.12873",
  "fulltext_url": null,
  "id": "754s104z6zrbg",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.12873",
  "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",
      "math-ph"
    ],
    [
      "arxiv",
      "math.MP"
    ],
    [
      "openalex",
      "3107|Quantum many-body systems"
    ]
  ],
  "openalex": "W7212981880",
  "pdf_url": "https://arxiv.org/pdf/2609.12873",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-11",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/754s104z6zrbg.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:07Z",
      "native_id": "2609.12873",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.12873"
    }
  ],
  "subjects": [
    {
      "field": "mathematics",
      "origin": "arxiv:math-ph",
      "subfield": "mathematical-physics"
    }
  ],
  "title": "Extremal States of Multipartite Quantum Spin Systems",
  "title_text": "Extremal States of Multipartite Quantum Spin Systems",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:11Z",
  "url": "https://research.draconitic.com/paper/754s104z6zrbg",
  "venue": "arXiv",
  "versions": []
}