After two decades of tinkering, scientists at NIST have unveiled the world’s most accurate atomic clock, a glowing achievement powered by quantum logic. This aluminum ion clock doesn’t just tick, it computes time to the 19th decimal place. That’s so precise, it could run for billions of years without missing a beat.
By pairing an aluminum ion with a magnesium ion, researchers harness quantum computing techniques to keep time ultra-tight.
Record-Breaking Features:
- 41% more accurate than the previous champ
- 2.6x more stable than any ion clock before it
- Precision upgrades from laser tuning to vacuum chamber engineering
Mason Marshall, NIST researcher and first author on the paper, said, “It’s exciting to work on the most accurate clock ever. At NIST, we get to carry out these long-term plans in precision measurement that can push the field of physics and our understanding of the world around us.”
Supercooling coupled ions for more accurate atomic clocks
Aluminum has the makings of a perfect timekeeper; its atomic “ticks” are ultra-steady, high-frequency, and barely flinch in response to environmental shifts, such as temperature or magnetic fields. It’s more stable than cesium, which still holds the official definition of the second.
But here’s the twist: aluminum doesn’t play well with lasers. It’s shy, tricky to cool or probe, two things atomic clocks need.
So researchers gave aluminum a friend: magnesium. Magnesium may not have flawless ticks, but it’s laser-friendly and acts as a supportive sidekick in what’s known as quantum logic spectroscopy.
- Magnesium cools down aluminum.
- It mirrors aluminum’s motion.
Scientists read aluminum’s “clock state” by watching magnesium’s behavior.
World’s first optical atomic clock with highly charged ions
This clever ion buddy system helps scientists tame aluminum’s brilliance while making it readable, reactive, and remarkably precise. Together, they built a quantum logic clock that not only keeps time but also sets the standard for precision.
One big challenge? The ion trap, where aluminum and magnesium ions are held. Think of it like a tiny arena, but the floor had issues. Tiny jolts, known as excess micromotion, were causing the ions to jitter, disrupting their perfect tick-tock rhythm.
The fix:
Scientists redesigned the trap’s base using a thicker diamond wafer for added stability. They adjusted the gold coatings on the electrodes to rebalance the electric fields and increased their thickness to reduce resistance.
These changes calmed the ions down, eliminating the unwanted wiggles and letting them tick with serene, uninterrupted precision, like a clock finally finding its rhythm.
A new kind of atomic clock possibly reveal new physics
Even the world’s best atomic clock can get hiccups, especially from invisible villains like hydrogen.
Tiny traces of hydrogen were escaping from the steel vacuum chamber and colliding with the ions, disrupting their rhythmic ticking. These collisions meant the team had to reload the clock’s ions every 30 minutes… not ideal when you’re chasing nanosecond perfection.
Solution? Titanium makeover.
By rebuilding the chamber out of titanium, they reduced background hydrogen by 150 times, allowing the clock to run for days without needing a refresh.
But the clock had one more demanding requirement: a super-stable laser to measure the ion’s ticks without introducing noise. The 2019 version relied on weeks of averaging to smooth out quantum jitters caused by the laser itself.
Enter Jun Ye’s team at JILA, wielding one of the most stable lasers in the world—the same powerhouse behind the record-holding Strontium 1 lattice clock. With this upgrade, tick-counting became ultra-clean and reliably crisp.
NASA activates deep space atomic clock
To build the most precise clock in human history, the team needed a laser so stable it wouldn’t flinch at the quantum level. Their solution? A 2-mile fiber-optic handoff across town.
Using underground fiber links, physicist Jun Ye’s team at JILA beamed their ultra-stable laser 3.6 kilometers to Tara Fortier’s lab at NIST. There, a “frequency comb”, a ruler for light, helped synchronize the aluminum ion clock’s laser to match Ye’s. It’s like tuning a musical instrument to perfection… using a beam of light.
With this upgrade:
- The ion probing time jumped from 150 milliseconds to a full second.
- Measurement speed increased dramatically, down to the 19th decimal place in just 1.5 days, not 3 weeks.
- The clock’s stability broke records, making it a landmark in timekeeping.
But it’s not just about counting seconds. This clock can now:
- Help redefine the official length of a second
- Serve as a testbed for quantum physics and logic operations.
- Assist in Earth geodesy, making precision measurements of Earth’s shape and gravitational field.
- Probe deep physics questions, like whether the fundamental constants of nature are secretly shifting over time.
“With this platform, we’re poised to explore new clock architectures, like scaling up the number of clock ions and even entangling them, further improving our measurement capabilities.”
Journal Reference:
- Mason C. Marshall, Daniel A. Rodriguez Castillo, Willa J. Arthur-Dworschack, Alexander Aeppli, Kyungtae Kim, Dahyeon Lee, William Warfield, Joost Hinrichs, Nicholas V. Nardelli, Tara M. Fortier, Jun Ye, David R. Leibrandt, and David B. Hume. High-stability single-ion clock with 5.5×10−19 systematic uncertainty. Physical Review Letters. DOI: 10.1103/hb3c-dk28