It is so accurate that the clock won’t lose or gain even a second for several billion years!
Do the clocks in your home and car always seem to be different? Do you feel like you never know what the right time is? Well, maybe all you need is a clock that keeps time according to the movement of ytterbium ions.
Enter the most accurate clock on Earth.
The clock was built by German physicists and it is called an optical single-ion clock. It works by measuring the vibrational frequency of ytterbium (Yb) ions as they oscillate back and forth between two different energy levels hundreds of trillions of times per second .
It is hard to imagine anything moving that fast.
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The ions are trapped in an optical lattice of laser beams, which allows scientists to count the number of ytterbium ticks per second. It is so accurate that the clock won’t lose or gain even a second for several billion years!
Ytterbium ions — a rare earth, soft and silver chemical element — are perfect for the clock, because they can transition between two states while giving a clear and measurable tick. “One of these transitions is based on the excitation into the so-called 'F state' which, due to its extremely long natural lifetime (approximately six years), provides exceptionally narrow resonance,” the team explained in a press release.
Previously, the most accurate keepers-of-time were cesium atomic clocks. Cesium clocks contain a pendulum of atoms that are excited by microwave radiation, and these clocks are what the official definition of a second — the Standard International (SI) unit of time — is based on.
According to the most accurate cesium atomic clock, one second is the time that passes when 9,192,631,770 cycles of the radiation produced by the transition between two levels of the caesium 133 atom. But clearly, I guess you can never be too accurate.
In fact, this new ytterbium clock is 100 times more accurate than the most accurate cesium clock. “It is regarded as certain that a future redefinition of the SI second will be based on an optical atomic clock,” the team said. “These have a considerably higher excitation frequency [...] which makes them much more stable and more accurate than caesium clocks.”
Although several of these clocks have been built in the past, this latest version is the first to attain an accuracy that so far had only been predicted in theory.
Let’s put it this way: You could never use the excuse for being late by saying the time was wrong on your stove if you had a ytterbium clock. But don’t worry, we probably never will, so we don’t have to get too creative quite yet.