{
  "abstract": "We introduce PULSUS, a direct frequency-domain framework for multidimensional spectroscopy of open quantum systems beyond the impulsive rotating-wave approximation. Coherence-frequency intervals are represented through Liouvillian resolvents, while finite Gaussian pulses are incorporated through operator-valued functions of the field-free Liouvillian. This enables direct evaluation on Cartesian grids or arbitrary spectral coordinates while retaining molecular evolution during the pulse envelopes and, when required, the complete light--matter interaction. The implementation is validated against analytical and independent time-domain benchmarks and supports targeted spectral sampling that reduces the number of evaluated coordinates when the response is spectrally localized. A controlled hierarchy of finite-pulse, rotating-wave, short-pulse, and impulsive models separates the errors introduced by each approximation. For a coupled electronic dimer, the total impulsive-RWA error is nonmonotonic in pulse duration: an intermediate regime provides the highest accuracy, whereas ultrashort pulses expose coupling-enabled beyond-RWA pathways and longer pulses develop substantial finite-pulse corrections. These results show that the impulsive and rotating-wave approximations cannot be assumed to improve simultaneously and should be tested when quantitatively interpreting multidimensional spectra. PULSUS provides a direct frequency-domain framework for carrying out that comparison.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.18712",
  "author_total": 2,
  "authors": [
    {
      "name": "Alfonso Castillo-Gonzalez"
    },
    {
      "name": "Eric R. Bittner"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1b8mv36cze5ds.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.18712",
  "fulltext_url": null,
  "id": "1b8mv36cze5ds",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.18712",
  "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|Spectroscopy and Quantum Chemical Studies"
    ]
  ],
  "openalex": "W7221807699",
  "pdf_url": "https://arxiv.org/pdf/2610.18712",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1b8mv36cze5ds.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:31Z",
      "native_id": "2610.18712",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.18712"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "PULSUS: Direct Frequency-Domain Multidimensional Spectroscopy Beyond the Impulsive Rotating-Wave Approximation",
  "title_text": "PULSUS: Direct Frequency-Domain Multidimensional Spectroscopy Beyond the Impulsive Rotating-Wave Approximation",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:31Z",
  "url": "https://research.draconitic.com/paper/1b8mv36cze5ds",
  "venue": "arXiv",
  "versions": []
}