{
  "abstract": "Changing a many-body system by one constituent is normally expected to produce only a vanishing correction to an intensive observable. Here we show that, above a critical dissipation imbalance, adding or removing one spin at fixed intensive controls switches the steady state of a dissipative collective spin between a phase-averaged ring and a south-polar fixed point. Unlike previous one-spin sensing through dark-state interference, parity here determines whether the Dicke ladder samples an interior zero of the nonlinear jump amplitude. The integer-spin ladder samples this zero, making Dicke states with m<0 transient, whereas the half-integer ladder misses it and remains a single recurrent class. Exact finite-size steady states show that exponential competition between stationary weights amplifies this microscopic connectivity difference, yielding a first-order dissipative phase transition confined to the odd-N sequence. Multisector one-spin loading and state-unresolved removal confirm the switch, while the exponentially increasing switching time reflects the metastable isolation of the competing macroscopic basins. Our results establish representation-lattice sampling as a route to phase control, suggesting parity-based detection of single-spin addition or removal.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.28390",
  "author_total": 1,
  "authors": [
    {
      "name": "Jianwen Jie"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5jswj9zwtfnjf.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.28390",
  "fulltext_url": null,
  "id": "5jswj9zwtfnjf",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.28390",
  "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",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Quantum optics and atomic interactions"
    ]
  ],
  "openalex": "W7204766733",
  "pdf_url": "https://arxiv.org/pdf/2608.28390",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5jswj9zwtfnjf.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2608.28390",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.28390"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "A Single Spin Switches the Steady-State Phase of an Open Quantum System",
  "title_text": "A Single Spin Switches the Steady-State Phase of an Open Quantum System",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/5jswj9zwtfnjf",
  "venue": "arXiv",
  "versions": []
}