World’s most accurate clock unveiled: Unique wonder of America’s NIST lab – 10 special things

1. The most accurate clock ever

• Developed by NIST, this clock has an accuracy of up to 19 decimal places, which makes it 41% more accurate than any previous clock.

2. Number one in stability too.

• This new aluminum-ion-based clock is not only the most accurate but is also 2.6 times more stable than all other ion clocks.

3. What is ‘accuracy’ and ‘stability’?

Clocks are tested on two parameters:

• Accuracy: How accurately it measures ‘real time.’
• Stability: How effective and repeatable measurements it gives.
• This clock is at the top on both these parameters.

4. Why choose aluminum ion?

• The aluminum ion is extremely stable and “ticks” at a high frequency, making it an extremely reliable timekeeper. It is also less affected by temperature and magnetic effects.

5. But there are some challenges too.

• Cooling and reading aluminum ions with a laser is extremely challenging. This has been a hindrance in the expansion of this technology.

6. Solution: Magnesium

• The team combined aluminum ions with magnesium ions to solve this problem.
• Magnesium is easily controlled and with the help of quantum logic spectroscopy, it cools the aluminum and makes it readable.

7. Changes in the trap design as well

• Excess micromotion was observed in the trap in which the ions are kept, which was reducing the accuracy of the clock. To fix this, the team redesigned the trap on a thick diamond wafer and also thickened the gold coating so that the electric field became stable.

8. Improvement in the vacuum system

• Earlier, hydrogen gas used to come out from the steel vacuum chamber, which hindered the working of the clock. Now the new chamber has been made of titanium, which reduced the hydrogen gas by 150 times.

9. Experiments can now run for days without interruption.

• With this improvement, scientists can now run experiments for several days without having to repeatedly load ions, resulting in more accurate data.

10. New laser, new stability

• A more stable laser has been used to probe the ions, making counting every “tick” even more reliable.