{
  "abstract": "The positive-P representation for bosons allows scalable exact simulations of many-body open quantum systems, provided dissipation is strong enough to stabilise stochastic trajectories. Designing analogous methods for spin systems, relevant to quantum technologies, remains challenging, as previous spin positive-P formulations can exhibit systematic errors even when simulations are numerically stable. Here, we develop a phase-space representation that maps spin-$\\frac{1}{2}$ degrees of freedom onto parameters of a local generalized density matrix (GDM), rather than SU(2) coherent states. In all stable regimes, we observe no deviations from exact solutions, restoring the positive-P property: stable solutions are exact up to stochastic sampling noise. The GDM representation combines seamlessly with bosonic positive-P, enabling highly scalable treatment of coupled spin-boson systems. We map simulation stability versus spin and boson dissipation in the Jaynes-Cummings model and apply the method to a Jaynes-Cummings-Hubbard quasi-Lieb lattice, showing how spin dissipation and driving can destroy or restore excitation incompressibility.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.38059",
  "author_total": 4,
  "authors": [
    {
      "name": "Alex Ferrier"
    },
    {
      "name": "Yi Shi"
    },
    {
      "name": "Marzena H. Szymańska"
    },
    {
      "name": "Piotr Deuar"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7chwhpqafjynx.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.38059",
  "fulltext_url": null,
  "id": "7chwhpqafjynx",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.38059",
  "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",
      "quant-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.38059",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-27",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7chwhpqafjynx.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:36:23Z",
      "native_id": "2610.38059",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.38059"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Exact Positive-P Simulation of Open Quantum Spin Systems with Generalized Density Matrix Formalism",
  "title_text": "Exact Positive-P Simulation of Open Quantum Spin Systems with Generalized Density Matrix Formalism",
  "type": "preprint",
  "updated_at": "2026-11-01T12:20:44Z",
  "url": "https://research.draconitic.com/paper/7chwhpqafjynx",
  "venue": "arXiv",
  "versions": []
}