Redefining a Second of Time: The New Super-Precise Optical Lattice Clock

You'd think that a second would be a defined unit of time, unable to be altered by any means. Yet a new, super-precise clock, called an optical lattice clock may be changing that notion. The advanced clock possesses the precision and stability to provide a new standard for the international definition of a second of time.

Currently, scientists use atomic clocks to keep the most accurate time. Since the 1960s, this clock has been used to define a second in the International System of Units (SI units), according to BBC News. Just like how a grandfather clock uses the swing of a pendulum to measure intervals of time, an atomic clock uses the regular vibrations of atoms in order to measure units.

The most accurate way to currently tell time is using caesium fountains, according to Nature. Essentially, a laser beam propels atoms in gaseous caesium upward. Emission from the atoms is probed as they pass twice through a microwave beam. This allows the clock to accurately measure time. In fact, the clocks keep time to within one second over 100 million years.

The new optical lattice clocks, though, are far more accurate than these caesium fountains. First introduced less than a decade ago, they measure the frequency of visible light--rather like trapped-ion clocks. These frequencies are tens of thousands of times higher than that of microwaves. These clocks also measure the average emission frequency from several thousand trapped ions than just one, which makes the measurement statistics better.

In this latest study, researchers decided to put these optical lattice clocks to the test. They compared them against current atomic timekeepers and then compared two optical clocks with each other. It turns out that not only do they measure up well against other clocks, but they could also keep time in agreement--a crucial factor.

"For instance, if you have your wristwatch, and one day you are one second late, and one day one second early, then your clock is not stable," said Jerome Lodewyck from the Paris Observatory in an interview with BBC News. "But it could still have good accuracy if over a million days the time is correct."

Whether this clock will be used to redefine the second is still up for debate. Yet the latest findings reveal huge potential for the clock, which could eventually be used to make time that much more precise.

The findings are published in the journal Nature Communications.