Topic
Clocks referenced to a nuclear transition rather than an electron transition, currently at prototype stage using thorium-229.
TU Wien physicists have built a thorium nuclear clock that held its own laser steady for more than 24 hours without leaning on a conventional atomic clock. The university's release reports how long it ran but not how precisely it ticked, and that figure would show whether thorium can compete with today's atomic clocks.
Reality
Teams at PTB-TU Wien and Tsinghua report the first working nuclear clocks, locking UV lasers to thorium-229 nuclei after more than 20 years of effort. With two labs running one crystal design, results can now be reproduced and checked against atomic clocks.
Perspective Coverage
4 publishersReality
High-harmonic X-ray sources normally emit only at integer multiples of their driving laser. A TU Wien and UC San Diego method detunes the driver instead, filling in the frequencies between two neighbouring harmonics.
Reality
Physicists reporting in Nature drove the 8.4-electronvolt nuclear transition in a thorium-doped calcium fluoride crystal and read the resonance as a dip in the transmitted beam, a detection route that works without waiting for the excited nucleus to decay.
Reality
After more than 15 years of crystal work, Thorsten Schumm's group found the one lattice position that answers on a single wavelength. The two precision figures in the account sit a factor of 100 apart.
Reality
A Science paper maps the four places a thorium-229 atom can sit in a calcium fluoride crystal and finds only one with a clean nuclear transition. That turns a materials guess into a spec.
Reality