By Alimat Aliyeva
Scientists at the US National Institute of Standards and
Technology (NIST) have successfully developed the most accurate
atomic clock in the world. This groundbreaking aluminum-ion-based
clock can measure time with an astonishing precision of up to 19
decimal places. The results of the research were published in
Physical Review Letters (PRL), Azernews
reports.
Modern optical clocks are typically assessed on two key metrics:
accuracy, which refers to how closely the clock’s time matches the
reference time, and stability, which describes how smoothly and
consistently the clock’s ticking behaves. The new NIST clock has
proven to be not only 41% more accurate than the previous ion
clocks but also 2.6 times more stable. These results were the
product of 20 years of research and refinement, improving
everything from the lasers used to the vacuum chambers housing the
clock.
The centerpiece of this breakthrough clock is the aluminum ion,
chosen for its extraordinarily stable “ticking” frequency.
“Aluminum turned out to be even better than the traditional
cesium-based clocks, which form the foundation of the current
international time standard. It’s far less sensitive to
environmental factors such as temperature shifts and magnetic
fields,” explained physicist David Hume, one of the lead
researchers on the project.
While aluminum’s properties were ideal for creating such an
accurate clock, the challenge was that it is notoriously difficult
to cool and synchronize with a laser. To solve this, the team added
a second ion, magnesium. Magnesium is easier to manipulate and
“assists” the aluminum by cooling it and providing feedback about
its behavior. This innovative approach is known as quantum logic
spectroscopy.
“Magnesium and aluminum move in tandem, and by using magnesium,
we can accurately read the behavior of aluminum—this is how our ion
system works,” explained graduate student Willa
Arthur-Dvorshak.
Achieving such unprecedented accuracy required overcoming
numerous physical obstacles. For example, the ions would
occasionally shift slightly inside the trap due to microscopic
electrical imbalances, which caused errors. This was addressed by
redesigning the electrode coating and reinforcing the trap
structure with a diamond plate to maintain stability.
Another challenge emerged from the hydrogen released by the
steel walls of the vacuum chamber. When this hydrogen collided with
the ions, it disrupted the clock’s stability. To resolve this, the
researchers replaced the steel with titanium, which reduced the
hydrogen levels by a factor of 150. This modification allowed the
clock to operate continuously for several days, whereas before, it
would require reloading every half hour.
“Building such a clock is incredibly fascinating. We’re working
at the frontier of fundamental physics,” said lead author Mason
Marshall, a physicist at NIST.
This atomic clock could revolutionize fields that require
extreme precision, such as GPS systems, scientific experiments, and
even quantum computing. By providing a more stable and accurate
time standard, it could also improve the synchronization of data
across vast networks, making it essential for everything from
telecommunications to financial transactions.