{
  "annotation_id": "d03e1ee7-02d4-42c6-ab8f-c154691d23ed",
  "date_created": "2026-03-02T18:00:50.368000Z",
  "date_modified": "2026-03-02T18:00:50.368000Z",
  "file_hash": "889548cff4df8e1e35567558e60d583ec9f3003db2027e44141647e430355ff8",
  "private": false,
  "record": {
    "abstract": "The comparison of different atomic transition frequencies over time can be\nused to determine the present value of the temporal derivative of the fine\nstructure constant alpha in a model-independent way without assumptions on\nconstancy or variability of other parameters. We have measured an optical\ntransition frequency at 688 THz in ^{171}Yb+ with a cesium atomic clock at two\ntimes separated by 2.8 years and find a value for the fractional variation of\nthe frequency ratio $f_{\\rm Yb}/f_{\\rm Cs}$ of $(-1.2\\pm 4.4)\\cdot 10^{-15}$\nyr$^{-1}$, consistent with zero. Combined with recently published values for\nthe constancy of other transition frequencies this measurement sets an upper\nlimit on the present variability of alpha at the level of $2.0\\cdot 10^{-15}$\nyr$^{-1}$, corresponding so far to the most stringent limit from laboratory\nexperiments.",
    "arxiv_id": "physics/0402132",
    "authors": [
      "E. Peik",
      "B. Lipphardt",
      "H. Schnatz",
      "T. Schneider",
      "Chr. Tamm",
      "S. G. Karshenboim"
    ],
    "categories": [
      "physics.atom-ph"
    ],
    "doi": "10.1103/PhysRevLett.93.170801",
    "journal_ref": "Phys. Rev. Lett. 93, 170801 (2004)",
    "title": "New limit on the present temporal variation of the fine structure   constant",
    "url": "https://arxiv.org/abs/physics/0402132"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "f3234d97-e3fa-426d-87d7-96cb1bf011bf",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}