Topic
Clocks that keep time by the frequency of an atomic transition, used as primary frequency standards and in satellite navigation and network synchronisation.
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
National University of Singapore physicists report in Nature a lutetium clock that measures a second about four times more accurately than any before it. It still fills a laboratory, so field uses such as monitoring magma underground wait on a transportable version.
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
JQI and Auckland researchers report in Nature a two-laser chip frequency comb that, they say, matches tabletop combs on routine measurement tasks. Portable atomic clocks are the goal, though the reported tests are bench measurements.
Reality
Physicists including Singapore's Murray Barrett report in Nature a lutetium-176 clock accurate to the 19th digit, 41% better than the prior record. The team pitches lutetium as cesium's successor in defining the second, where its tolerance of heat may count as much as the record.
Reality