The Beating Heart of “Father Time”


Photo by Andrew Brookes/National Physical Laboratory

National Physical Laboratory (NPL)–the place where the first atomic clock was made, have made recent development in ways to measure time even more accurately. According to their website, the current atomic clock system at NPL is the basis of all UK time, and the cutting-edge research being carried out is working to improve timekeeping accuracy even further.

Scientists at NPL built a super-accurate timekeeper, an optical atomic clock that promise significant advances than the ones that uses microwave frequencies.

When it comes to stability, optical atomic clocks are more reliable than atomic clocks operating at microwave frequencies because visible light has a frequency roughly 100 000 times higher than that of microwaves.

Potential applications of atomic clocks range from improved satellite navigation systems and better tracking of deep space probes to sensitive tests of general relativity and measurements of fundamental physical constants. They could even lead to the SI unit of time, the second, being redefined in future.

But how does this device work?
Every tick of this “clock” is governed by a single ion of the element strontium. This ion is trapped in an electromagnetic field within the small cube at the center and cooled with lasers to just fraction above absolute zero. The lasers are fired through three of the glass emanating from the cube, but must be carefully directed out of the other side to prevent them scattering within the clock, which is why there are six shafts in total, as reported by Jacob Aron.

Once the ion is cooled, another laser makes it resonate between two energy states with an incredible regularity governed by quantum mechanics. It gives off a regular pulse of optical radiation exactly 444, 779, 044, 095, 485 times per second, said in an article published online by

Thanks to NPL’s caesium fountain, NPL-CsF2, the currently most accurate clock in the world, able to measure the SI second more precisely than any other clock. This conclude that NPL plays a major role in the worldwide accurate time systems.


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