Azernews.Az

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.