NIST Ion Clock Sets New Record for Most Accurate Clock in the World
Summary
Researchers at the National Institute of Standards and Technology (NIST) have upgraded their trapped aluminium-ion optical clock and set a new world record for accuracy: reliable timekeeping to 19 decimal places. The improved aluminium-ion clock is 41% more accurate than the previous record and 2.6 times more stable than any other ion clock, following two decades of progressive refinements.
Key technical advances include a redesigned ion trap mounted on a thicker diamond wafer with modified, thicker gold electrode coatings to reduce excess micromotion; a new titanium vacuum chamber that cuts background hydrogen by 150× and allows days-long runs without reloading; and access to an ultrastable laser from Jun Ye’s JILA lab delivered over a 3.6 km fibre link and compared via a frequency comb, which extended probe times from 150 ms to one second and shortened averaging time from weeks to about a day and a half.
The work, published in Physical Review Letters, strengthens efforts to redefine the second, improves capabilities for precision geodesy, and opens new routes for quantum-logic experiments, including scaling to multiple ions and entanglement-based clocks.
Key Points
- NIST’s aluminium-ion clock now achieves accuracy to 19 decimal places, setting a new world record.
- The clock is 41% more accurate and 2.6× more stable than previous ion-clock records.
- Trap redesign (diamond wafer and thicker gold electrode coatings) reduced excess micromotion that previously disturbed the ions.
- A titanium vacuum chamber reduced background hydrogen by ~150×, extending experimental run times from minutes to days.
- Stability improvements came from linking to an ultrastable laser at JILA via a 3.6 km fibre and using a frequency comb, allowing 1 s probes instead of 150 ms.
- Averaging time to reach the 19th decimal place fell from ~3 weeks to about 1.5 days.
- Implications include contributing to the redefinition of the second, improved geodesy, and new tests of fundamental physics and quantum technologies.
Why should I read this?
Short version: this isn’t just a slightly better clock — it rewrites what we can measure about time, gravity and maybe even fundamental constants. If you care about precision tech, quantum advances or the next definition of the second, this saves you the deep dive: big engineering fixes, a clever ion “buddy system” with magnesium, and a laser link that slashed measurement time.