{
  "abstract": "Rydberg atoms occupy a central role in quantum science; their loosely bound outer electron gives rise to properties that enable quantum information processing1 or the formation of exotic molecular bonds2. Beyond these roles, they have been proposed as a neutral platform for the observation of quantum effects in collisions and reactions of the ionic core with neutral particles3, 4, a long-standing goal of ion-based chemistry and physics. However, all of the experimental results so far could be explained using a classical description of the internuclear motion5. Here we demonstrate cold collisions inside a Rydberg helium atom, achieved by merging helium Rydberg and ground-state helium beams and imaging individual scattering events. We resolve the fully quantum-coherent motion and observe matter-wave diffraction and tunnelling-driven shape resonances down to collision energies of 90 mK. In the case of identical helium nuclei, we demonstrate a new regime of identical-particle Mott interference6, where quantum statistics begin to govern the total scattering cross section. For distinct isotopes, we show the breakdown of the Born-Oppenheimer approximation and benchmark parameter-free, state-of-the-art theory. We directly measure the helium isotope ionization-energy difference to be 15.0 +/- 0.1 K. Our experiments establish Rydberg atoms as a platform for the direct observation of quantum dynamics with a general class of ions, atoms and molecules.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.18345",
  "author_total": 9,
  "authors": [
    {
      "name": "Arijit Das"
    },
    {
      "name": "Yufeng Wang"
    },
    {
      "name": "Marcin Welter"
    },
    {
      "name": "Karl Horn"
    },
    {
      "name": "Dawid Dąbrowski"
    },
    {
      "name": "Michał Przybytek"
    },
    {
      "name": "Julia Narevicius"
    },
    {
      "name": "Michał Tomza"
    },
    {
      "name": "Edvardas Narevicius"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/857b0x5v1mmf3.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.18345",
  "fulltext_url": null,
  "id": "857b0x5v1mmf3",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.18345",
  "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",
      "physics.atom-ph"
    ],
    [
      "arxiv",
      "physics.chem-ph"
    ],
    [
      "openalex",
      "3107|Cold Atom Physics and Bose-Einstein Condensates"
    ]
  ],
  "openalex": "W7221753453",
  "pdf_url": "https://arxiv.org/pdf/2610.18345",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/857b0x5v1mmf3.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:11Z",
      "native_id": "2610.18345",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.18345"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "arxiv:physics.chem-ph",
      "subfield": "physical"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.atom-ph",
      "subfield": "amo"
    }
  ],
  "title": "Collision inside an atom: quantum ion-atom dynamics",
  "title_text": "Collision inside an atom: quantum ion-atom dynamics",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:11Z",
  "url": "https://research.draconitic.com/paper/857b0x5v1mmf3",
  "venue": "arXiv",
  "versions": []
}