{
  "id": 12663736,
  "title": "Nuclear clocks finally see the light",
  "url": "https://urgent.news/2026/10/07/nuclear-clocks-finally-see-the-light",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-07T16:00:48.000Z",
  "source": {
    "name": "Physics World",
    "slug": "physics-world",
    "url": "https://physicsworld.com/a/nuclear-clocks-finally-see-the-light/"
  },
  "original_language": "en",
  "account": "Two separate research groups have successfully created the first nuclear clocks, a significant breakthrough in precision timekeeping. These new clocks could play a crucial role in testing fundamental physics principles. Currently, atomic clocks, which measure time based on electron transitions, rely on microwave frequencies. However, nuclear clocks, which utilize higher-frequency ultraviolet transitions within atomic nuclei, could offer even greater precision.\n\nThe idea of nuclear clocks dates back to the late 1990s, but their practical implementation has proven challenging. These clocks require highly stable lasers with extremely narrow bandwidths to excite narrow nuclear transitions. While the first team, led by Ekkehard Peik from the Physikalisch-Technische Bundesanstalt (PTB) and TU Wien in Austria, demonstrated laser excitation of thorium-229 nuclei and embedded them in crystals, the second team, led by Shiqian Ding from Tsinghua University and including collaborators from China, developed a method for growing small single crystals of thorium-229 at a lower isotope concentration.\n\nBoth groups used millimeter-sized crystals of calcium fluoride (CaF2) containing thorium-229 and stabilized their lasers through direct absorption spectroscopy and feedback loops. The PTB-TU Wien collaboration produced a stabilized nuclear clock with a fractional frequency instability of 3 x 10^-12 /√τ/s, while the Tsinghua team achieved a lower fractional instability of 5 x 10^-13 /√τ/s. Both teams reported that their clock frequencies aligned with previous measurements of thorium-229 transitions.\n\nThe PTB-TU Wien team employed their nuclear clock to search for ultralight scalar dark matter interactions and constrain fluctuations in the nuclear transition energy. Meanwhile, the Tsinghua team focused on technical improvements such as high-power vacuum ultraviolet laser interrogation and clock performance. Both teams are now working on further enhancing the performance of their nuclear clocks by increasing laser power, improving detector signal-to-noise ratios, and optimizing crystal structures to achieve even narrower nuclear transition linewidths.",
  "summary": "New timekeeping tools could revolutionize studies of fundamental physics The post Nuclear clocks finally see the light appeared first on Physics World .",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}