Atomic Optical Clock’s Heart as Small as a Coffee Bean

In case you didn’t know how these clocks function precisely, the scientists say they track time by counting the oscillations of light absorbed by cesium atoms. And now, they have become more practical than ever.

Atomic Clocks Are Becoming Portable

At first, atomic clocks were quite huge, but as of lately, scientists are doing their best to make them practical and small. At least small enough for everyday human use. For now, we do have a smaller, somewhat miniature version of a type of an optical clock. Although these two are quite similar, they still operate under different principles. The optical clock uses light tuned to rubidium atoms, and it beats about trillions of times per second. Their purpose is to tell the time more precisely than the regular clocks we have. Considering they divide time into such short intervals makes them much more reliable.

In order to function correctly, an optical clock needs to have a heart, or a chamber as many refer to it. Inside this heart, there needs to be a chamber of atoms — but considering how big optical clocks are, this chamber can be a couple of meters wide. Well, in the atomic optical clock, this chamber is merely a couple of millimeters wide. Additionally, it is stuck to a silicon chip. Silvio Koller, a scientist who worked at the German National Metrology Institute, says that he is astonished anyone managed to produce such a small heart.

Believe it or not, these small optical clocks are not irrelevant to us, common people. They could improve our Internet, and general telecommunication by far. The pendulum of the clock is laser tuned to 385.285 THz, which means that its light moves 385.285 trillions of times in only one second. And just to make sure that the laser’s oscillations don’t fall out of rhythm, one part of the beam goes inside the rubidium atoms chamber. This chamber absorbs light with the exact same frequency.

This process tells the laser if it needs to dial its frequency down or up in order to tell time more precisely. For this reason, it is imperative for the clock to know where rubidium atoms are absorbing any light.

This technology still cannot be implemented into modern technology as it’s not fast enough to catch up with the frequency of the laser.

Now, here’s the main difference between an optical clock and cesium-based metronomes. The optical clock produces ticks at 22 gigahertz, which is as twice as much as the cesium-based one. This is because the optical clock’s gigahertz have shorter terahertz beats, which makes them much more accurate than those of cesium-based clock. If you sum it all up, that makes current cesium-based optical clocks at least 50 times better and more accurate, says Matthew Humon.

This new optical clock might be a lot smaller than its ancestors, but it still isn’t the size of a pocket watch. That’s due to the chip-scale chamber being attached to bigger electronics that support its function. For now, this clock is big enough to put on two tables, but according to Hummon, scientists do share the ambition to make it hand-sized.