A new study showed that a pair of atomic clocks set "unprecedented" performance indicators for stability and accuracy.
Researchers say record results can help improve timing and navigation.
Physicists at the National Institute of Standards and Technology (NIST) in the United States said that two bars would also help explore gravity, the early universe, and even dark matter.
On experimental devices, each trap contains thousands of atoms of the chemical element ytterbium in grids of laser beams.
Inside these optical arrays, atoms are called “ticking”, vibrating between two energy levels.
In a study published in the journal Nature, NIST physicists compared two independent watch movements and reached record levels in the areas of systematic uncertainty, stability, and reproducibility.
Systematic uncertainty measures how well clocks represent natural vibrations or atomic frequencies.
The researchers found that each clock cycle corresponds to a natural frequency with an error of 1 billion billion.
The stability of hours, the value that changed during the day, was also recorded at the minimum level.
The reproducibility of the results, how close both sentries appeared at the same frequency, again showed a difference of less than one billionth of a billion.
“System uncertainty, stability and reproducibility can be considered the“ royal flush ”of performance for these watches,” said project manager Andrew Ludlow.
"The agreement of two hours at this unprecedented level, which we call reproducibility, is perhaps the most important result, because it essentially requires and substantiates two other results."
Mr. Ludlow said that the total clock error decreased below the ability of scientists to take into account the effect of gravity on time.
“We assume that clocks like these are used throughout the country or the world, their relative performance will be limited for the first time to the gravitational effects of the Earth,” he said.
According to the famous theory of relativity, physicist Albert Einstein, time passes more slowly in places with stronger gravity.
The researchers claim that the uncontrolled timekeeping of the supersensitive NIST clocks will help with accurate display of the gravitational distortion of space-time.
They also claim that it will help with the detection of signals from the early universe, such as mysterious dark matter.
Ytterbian clocks could also improve the ability to measure the shape of the Earth based on surveys of sea levels.
Devices placed on different continents can resolve geodetic measurements with an accuracy of one centimeter.
The ytterbium atom is among the potential candidates for the future redefinition of the second, international time unit in terms of optical frequencies.
The new NIST watch records show a 100-fold increase in clock accuracy based on the current standard, the cesium atom, which vibrates at lower microwave frequencies.
Researchers are now building an ytterbium lattice watch that could be transported to other laboratories around the world to compare clocks.