{
  "abstract": "Strongly correlated quantum systems, including frustrated spin lattices, remain challenging for conventional coupled-cluster methods because their ground states often exhibit strong multireference character and symmetry breaking. Although multireference and symmetry-projected coupled-cluster theories are promising, they are not yet black-box methods and require system-specific development. The XXZ and $J_1$-$J_2$ spin models provide demanding benchmarks. Spin-BCS-based coupled-cluster methods may require high excitation ranks to recover the exact ground-state physics in strongly correlated regimes. We introduce a nonlinear spin-fermion-spin (SFS) transformation designed to map a strongly correlated spin Hamiltonian into a new spin Hamiltonian whose ground state is more accurately described at the mean-field level. For a representative SFS transformation, we identify a compact Clifford circuit that maps transformed product states to circuit-dressed, generally entangled states in the original representation. The transformed Hamiltonian can then be treated using broken-symmetry mean-field theory and post-mean-field methods. Benchmarks for the XXZ and $J_1$-$J_2$ Hamiltonians show that spin mean-field theory in the transformed representation reduces the energy error relative to conventional spin-BCS mean field. The spin-BCS-based coupled-cluster calculations for the one-dimensional XXZ model provide substantially improved accuracy relative to the corresponding untransformed methods. In 2D, the accuracy of the transformed mean-field solutions depends on the site ordering and boundary conditions, as nonlocal strings can appear. These results show that exact transformations of operator representations can serve as many-body preconditioners for mean-field and low-rank coupled-cluster approximations to strongly correlated spin systems.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.30403",
  "author_total": 3,
  "authors": [
    {
      "name": "Swarnamoy Ghosh"
    },
    {
      "name": "Thomas M. Henderson"
    },
    {
      "name": "Gustavo E. Scuseria"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dkxdtzk359vag.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.30403",
  "fulltext_url": null,
  "id": "dkxdtzk359vag",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.30403",
  "language": null,
  "licence": "CC-BY-NC-ND-4.0",
  "licence_label": "CC BY-NC-ND 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.other"
    ],
    [
      "arxiv",
      "cond-mat.str-el"
    ],
    [
      "openalex",
      "3107|Quantum many-body systems"
    ]
  ],
  "openalex": "W7223381304",
  "pdf_url": "https://arxiv.org/pdf/2610.30403",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dkxdtzk359vag.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.30403",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.30403"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.other",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Nonlinear Canonical Transformations for Studying Spin-1/2 Hamiltonians",
  "title_text": "Nonlinear Canonical Transformations for Studying Spin-1/2 Hamiltonians",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/dkxdtzk359vag",
  "venue": "arXiv",
  "versions": []
}