{
  "abstract": "The fate of quantum coherence following photoexcitation is a central problem in nonequilibrium condensed-matter physics, especially in low-dimensional solids where electronic, structural and many-body energy scales are strongly coupled. Here, we investigate this interplay in ferroelectric $α$-In$_{2}$Se$_{3}$ using broadband transient-grating spectroscopy with $\\sim$5 fs laser pulses. Photoexcitation launches pronounced oscillations dominated by a $\\sim$104 cm$^{-1}$ mode that persists for several picoseconds. Measurements from 10 to 300 K show that its frequency remains nearly unchanged while its coherence is progressively suppressed, distinguishing the lattice coordinate from thermally activated dephasing. Varying excitation energy reveals a distinct crossover in which increasing photoexcitation progressively modifies and damps the coherent response. First-principles calculations assign the dominant oscillation to a 101.47 cm$^{-1}$ $Γ$-point optical phonon involving collective In-Se displacement, while quantum-dynamical simulations reproduce the main transient-grating oscillations. These results establish $α$-In$_{2}$Se$_{3}$ as a model system for independently probing lattice coherence, thermal fluctuations and carrier-density-dependent interactions, revealing how a polar van der Waals semiconductor evolves from coherent lattice motion toward an incoherent many-body state after ultrafast excitation.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.04863",
  "author_total": 7,
  "authors": [
    {
      "name": "Xuanchao Zhang"
    },
    {
      "name": "Dehao Yuan"
    },
    {
      "name": "Junhua Zhou"
    },
    {
      "name": "Vandana Tiwari"
    },
    {
      "name": "Fulu Zheng"
    },
    {
      "name": "Ajay Jha"
    },
    {
      "name": "Hong-Guang Duan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/9t1mc8wfjgr70.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.04863",
  "fulltext_url": null,
  "id": "9t1mc8wfjgr70",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.04863",
  "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.atm-clus"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "3104|Advanced Condensed Matter Physics"
    ]
  ],
  "openalex": "W7220657523",
  "pdf_url": "https://arxiv.org/pdf/2610.04863",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-04",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/9t1mc8wfjgr70.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2610.04863",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.04863"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.atm-clus",
      "subfield": "amo"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Long-lived Coherent Phonons Reveal Competing Thermal and Many-Body Dynamics in $α$-In$_{2}$Se$_{3}$",
  "title_text": "Long-lived Coherent Phonons Reveal Competing Thermal and Many-Body Dynamics in α-In_2Se_3",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/9t1mc8wfjgr70",
  "venue": "arXiv",
  "versions": []
}