{
  "abstract": "The interaction of two qubits with a common bosonic reservoir is encoded by a matrix-valued spectral density $\\mathbf{J}(ω)$, whose diagonal entries describe the local spectra, while the off-diagonal entries encode cross-correlations. Even when \\(\\mathbf{J}(ω)\\) has rank one, a frequency-independent dark channel need not exist because the family \\(\\{\\mathbf{J}(ω)\\}_ω\\) may have a trivial common kernel. We term the frequency-dependent rotation of the bright and dark directions \\textit{spectral twisting} and quantify it through the Fubini--Study speed $τ(ω)$ of the bright spectral projector. We analyze how twisting modifies two-qubit dynamics and quantify the loss of dark-state protection through the leakage \\(P_{\\mathrm{leak}}(t)\\). Comparisons with untwisted asymmetric reservoirs and rotating-wave dynamics, together with detuned and finite-temperature calculations, distinguish spectral twisting from coupling asymmetry, counter-rotating processes, and thermal absorption. For resonant qubits tuned to the crossing of the two local spectra $ω_\\times$, the singlet is locally dark at the transition frequency but couples to off-resonant components whose bright directions are rotated. In the weak-twisting regime, the fixed-time leakage scales as $P_{\\mathrm{leak}}(t)\\propto[ω_\\timesτ(ω_\\times)]^2$. We test this prediction for mismatched Drude-Lorentz spectra using nonperturbative hierarchical equations of motion generalized to cross-correlated bath forces. These results provide a geometric framework for dark-state engineering in structured reservoirs.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.06802",
  "author_total": 3,
  "authors": [
    {
      "name": "Fabio Borrelli"
    },
    {
      "name": "Giovanni Miano"
    },
    {
      "name": "Carlo Forestiere"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fhfb9szbjhgbz.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.06802",
  "fulltext_url": null,
  "id": "fhfb9szbjhgbz",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.06802",
  "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": "W7212019198",
  "pdf_url": "https://arxiv.org/pdf/2609.06802",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/fhfb9szbjhgbz.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2609.06802",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.06802"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Spectral Twisting in a Common Bosonic Reservoir: Fragility of Two-Qubit Dark-State Protection",
  "title_text": "Spectral Twisting in a Common Bosonic Reservoir: Fragility of Two-Qubit Dark-State Protection",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/fhfb9szbjhgbz",
  "venue": "arXiv",
  "versions": []
}