Researchers at JILA, a US research institute, have developed a new light-based atomic clock that is so precise that it can measure the smallest effects predicted by Einstein’s general theory of relativity. The clock will lead to a more precise definition of a second and could even lead to the discovery of new underground mineral deposits, according to a press release from the organization.
Atomic clocks typically use microwaves to measure the length of a second. However, research has shown that illuminating atoms with visible light can help count the second much more accurately, since light waves have a higher frequency.
Light or optical atomic clocks could potentially lose a second in 30 billion years compared to microwave clocks. However, to achieve this accuracy, the clocks must be very precise, i.e. able to measure small fractions of a second.
Improving the precision of the atomic clock
Instead of a beam of visible light, the JILA researchers used a web of light, called an optical lattice, to measure tens of thousands of atoms at once. This gave the atomic clock more data to accurately measure the second.
While the optical lattice approach has been used before, JILA researchers used a relatively gentler approach to make their measurements. This helped reduce two sources of error: the laser itself measuring the atoms and the effect of the atoms bumping into each other when they are close together, the press release said.
Measuring the effects of relativity and more
According to Einstein’s general theory of relativity, gravity affects time. A stronger gravitational field results in a slower passage of time. The clock developed by JILA is sensitive enough to detect the effect of gravity on timekeeping at sub-millimeter scales.
Researchers observed subtle changes in the passage of time due to gravity when the clock was raised or lowered even slightly.
“It pushes the boundaries of what’s possible with timekeeping,” said Jun Ye, a physicist at JILA and NIST. But the clock design’s gains extend beyond these measurements into the quantum realm.
Quantum computers manipulate the properties of atoms and molecules to perform complex calculations. Because the JILA clock can make precise measurements, the researchers plan to use it in the microscopic domain, where theories of general relativity and quantum mechanics intersect, to measure the distortions in the flow of time at scales distorted by gravity.
At the same time, the clock’s precision could help scientists keep accurate time over extremely large distances in space. “If we want to land a spacecraft on Mars with extreme accuracy, we need clocks that are many times more accurate than what we have now in GPS,” Ye added in the press release.
“We’re pushing the boundaries of geometry. When you can measure things with this level of precision, you start to see phenomena that we’ve only been able to theorize about,” Ye concluded.
JILA is a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder.
The research results will be published in the journal Physical assessment letters.
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Ameya Paleja Ameya is a science journalist based in Hyderabad, India. A molecular biologist at heart, he traded in the micropipette to write about science during the pandemic and hasn’t looked back. He enjoys writing about genetics, microbes, technology, and public policy.