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This Optical Atomic Clock May Update Length Of A Second

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The world has been keeping time in the same way for about 50 years, but new and improved technologies may alter the standard even by a diminutive amount.

Scientists in Germany believe they have discovered a way to make the world's most accurate optical clock ever. This optical atomic clock has an extremely impressive timekeeping that if it had begun just after the Big Bang, it would have lost only 100 seconds.

Tick, Tock

All over the world, clocks rely on the counting of recurrent events with known frequency — such as the swinging of pendulum — to keep time.

Traditional atomic clocks measure the natural oscillation of the caesium atom. Since the late 1960s, the International System of Units (SI) has defined one second as the elapsed time between 9,192,631,770 cycles of caesium atom oscillations.

Although these atomic microwave clocks are accurate because they are based on universal atom vibrations, they can still commit an error of about 1 nanosecond every 30 days.

On the other hand, atoms in optical clocks swing about 100,000 times higher than atomic microwave clocks as they are in the visible or optical part of the electromagnetic spectrum. Higher frequencies mean optical clocks tick faster than atomic microwave clocks.

Again, these clocks still experience significant downtimes because of the complexity.

In order to deal with the downtimes, a team of scientists led by Dr. Christian Grebing combined a maser — or microwave spectral range laser — with an optical lattice made of strontium.

If a second was defined in a strontium optical clock, the equivalent unit in SI would be approximately 429,000 billion cycles. Researchers say this method reduces the error to 0.2 nanoseconds in just 25 days.

Practical Uses

It may seem as if the application of improved optical clocks could only work in theory, but Grebing says it's a milestone in terms of the practical implementation of optical clocks.

In fact, optical clocks could improve GPS-based navigation, electrical power grids, communication systems and financial networks.

"We want to improve the timekeeping infrastructure all over the world," says Grebing.

Scientists could achieve this goal by building better clocks and then integrating them into the timekeeping infrastructure, he said.

Financial networks with strontium optical clocks could use more precise time stamps and handle briefer transactions. GPS and satellite-based systems could offer even more exact information on locations.

Redefining The Length Of A Second

Could a strontium optical clock redefine the length of a second? Researchers say it's possible, but they believe a true redefinition may be years away. Grebing says holding off a redefinition of the SI unit makes sense until it is clear which of the types of clocks is best used for global timekeeping.

Additionally, although the length of a second, minute or hour could be altered, only a small amount would be added to the oscillation.

The details of the study are published in the journal Optica.

Photo: Phalinn Ooi | Flickr

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