{
  "abstract": "We present QuDPy-FDGF, an open-source Python framework that evaluates Liouville-space pathways as hybrid chains of time propagators and frequency-domain Green's functions. Frequency-resolved intervals are computed directly through shifted linear systems, without time propagation followed by a Fourier transform, while other intervals may remain in the time domain. A model-agnostic block interface separates the physical model from pathway construction, numerical propagation, and detection. The released implementation provides an explicit dense Liouville-space backend for reference calculations and a sector-resolved sparse backend using matrix-free generator actions, Krylov time propagation, and generalized minimal residual (GMRES) resolvent solves. Its observable layer reuses propagated pathway responses to evaluate operator expectation values, action-detected readout interactions, instantaneous jump rates, and integrated mean jump counts. The framework is assessed on an analytically solvable open two-level system and on two examples of increasing complexity: the complete third-order rephasing response, with its eight sequences, of a thermally initialized anisotropic Heisenberg (XXZ) spin chain with unequal excitation sectors, and two coupled dissipative anharmonic modes whose spectra depend on the detected observable, with the fifth-order double-quantum response of their closed limit. The calculations reproduce the analytical two-level response, check the matrix-free sparse evaluation against the dense assembly of the generator, and recover the harmonic-limit cancellation of the fifth-order signal when the required three-excitation manifold is retained. QuDPy-FDGF therefore provides a unified framework for pathway- and observable-resolved nonlinear spectroscopy in finite or truncated Hilbert spaces with unitary or Markovian Gorini--Kossakowski--Sudarshan--Lindblad (GKSL) dynamics.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.30398",
  "author_total": 6,
  "authors": [
    {
      "name": "Mathieu Desmarais"
    },
    {
      "name": "Simón Paiva-Ortega"
    },
    {
      "name": "Félix Brunell"
    },
    {
      "name": "Eric R. Bittner"
    },
    {
      "name": "Hao Li"
    },
    {
      "name": "Carlos Silva-Acuña"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/47txssfz34d27.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.30398",
  "fulltext_url": null,
  "id": "47txssfz34d27",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.30398",
  "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",
      "physics.chem-ph"
    ],
    [
      "arxiv",
      "physics.comp-ph"
    ],
    [
      "openalex",
      "3107|Laser-Matter Interactions and Applications"
    ]
  ],
  "openalex": "W7223373209",
  "pdf_url": "https://arxiv.org/pdf/2610.30398",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/47txssfz34d27.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.30398",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.30398"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "arxiv:physics.chem-ph",
      "subfield": "physical"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.comp-ph",
      "subfield": "computational"
    }
  ],
  "title": "QuDPy-FDGF: A Python-Based Tool for Computing Ultrafast Nonlinear Optical Responses Using Frequency Domain Green's Functions",
  "title_text": "QuDPy-FDGF: A Python-Based Tool for Computing Ultrafast Nonlinear Optical Responses Using Frequency Domain Green's Functions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/47txssfz34d27",
  "venue": "arXiv",
  "versions": []
}