{
  "abstract": "It is widely expected that the von Neumann entanglement of a local operator grows at most logarithmically in integrable many-body systems in infinite volume. We give a counterexample in a four-state brickwork circuit whose gate is a permutation matrix solving the constant Yang--Baxter equation. The von Neumann operator entropy grows as $(\\log2)\\sqrt{t/π}+O(\\log t)$, whereas fixed-index Rényi entropies grow linearly below index one and logarithmically above it. At fixed relative Hilbert--Schmidt error below one, matrix product operator simulations require a bond dimension growing at least as $\\exp(c\\sqrt t)$ for some $c>0$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.39401",
  "author_total": 1,
  "authors": [
    {
      "name": "Balázs Pozsgay"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/e455t376dh5fa.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.39401",
  "fulltext_url": null,
  "id": "e455t376dh5fa",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.39401",
  "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",
      "cond-mat.stat-mech"
    ],
    [
      "arxiv",
      "nlin.SI"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Quantum many-body systems"
    ]
  ],
  "openalex": "W7220892628",
  "pdf_url": "https://arxiv.org/pdf/2609.39401",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-06",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/e455t376dh5fa.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:22Z",
      "native_id": "2609.39401",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.39401"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.stat-mech",
      "subfield": "statistical-nonlinear"
    }
  ],
  "title": "Square-root growth of operator entanglement in an integrable brickwork circuit",
  "title_text": "Square-root growth of operator entanglement in an integrable brickwork circuit",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:22Z",
  "url": "https://research.draconitic.com/paper/e455t376dh5fa",
  "venue": "arXiv",
  "versions": []
}