{
  "annotation_id": "23b4330d-c8b4-4ac8-964f-e86b0831a7e3",
  "date_created": "2026-03-02T18:00:53.511000Z",
  "date_modified": "2026-03-02T18:00:53.511000Z",
  "file_hash": "260e119d8bd465fc8ddd4af5395abdef500aa7ad772326ec81155396e953b72a",
  "private": false,
  "record": {
    "abstract": "We have generated Coulomb crystals of ultracold $^4$He$^+$ ions in a linear\nradiofrequency trap, by sympathetic cooling via laser--cooled $^9$Be$^+$.\nStable crystals containing up to 150 localized He$^+$ ions at $\\sim$20 mK were\nobtained. Ensembles or single ultracold He$^+$ ions open up interesting\nperspectives for performing precision tests of QED and measurements of nuclear\nradii. The present work also indicates the feasibility of cooling and\ncrystallizing highly charged atomic ions using $^9$Be$^+$ as coolant.",
    "arxiv_id": "physics/0412053",
    "authors": [
      "B. Roth",
      "U. Fr\u00f6hlich",
      "S. Schiller"
    ],
    "categories": [
      "physics.atom-ph",
      "physics.plasm-ph"
    ],
    "doi": "10.1103/PhysRevLett.94.053001",
    "title": "Sympathetic cooling of $^4$He$^+$ ions in a radiofrequency trap",
    "url": "https://arxiv.org/abs/physics/0412053"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "4a0d70ec-daf2-425d-96de-491d09442a63",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}