{
  "abstract": "A resonant classical field drives a two-level system coherently and, with ordinary relaxation, produces saturation rather than directional population transfer. Here we show that directionality emerges when the excitation source is retained as a quantum subsystem and subsequently traced out. We model the source as a single-excitation degree of freedom, or equivalently a stream of two-level ancillas, exchange-coupled to a target two-level system. The source first moment generates the usual coherent drive, while its second moments produce upward and downward dissipative channels. For a number-diagonal, fully excited source, the first moment vanishes and only the upward channel remains, yielding monotonic pumping of the target. The same structure follows from both an exact collision map and a fluctuation-regulated second-order quantum master equation. For exponentially decaying source correlations, the pumping rate shows a Lorentzian detuning dependence governed by the correlation time $τ_c$, accompanied by a dispersive frequency shift. In the presence of thermal relaxation, the steady-state excited-state population can exceed the resonantly driven optical-Bloch limit of one half. Within the fluctuation-regulated master equation, this directional pumping arises as a drive-induced dissipative contribution whose strength and spectral response are controlled by $τ_c$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.34885",
  "author_total": 2,
  "authors": [
    {
      "name": "Sarfraj Fency"
    },
    {
      "name": "Rangeet Bhattacharyya"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5khp4tgw5f9nb.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.34885",
  "fulltext_url": null,
  "id": "5khp4tgw5f9nb",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.34885",
  "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",
      "3107|Quantum optics and atomic interactions"
    ]
  ],
  "openalex": "W7214739629",
  "pdf_url": "https://arxiv.org/pdf/2609.34885",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5khp4tgw5f9nb.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:12Z",
      "native_id": "2609.34885",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.34885"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Directional pumping of a two-level system by a fluctuation-regulated quantum source",
  "title_text": "Directional pumping of a two-level system by a fluctuation-regulated quantum source",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:12Z",
  "url": "https://research.draconitic.com/paper/5khp4tgw5f9nb",
  "venue": "arXiv",
  "versions": []
}