US builds world’s most accurate atomic clock ever to boost space science

Researchers at JILA, a US research institute, have developed a new light-based atomic clock that is so precise that it can measure the slightest effects, as predicted by Einstein’s theory of general 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, an organizational press release said.

Atomic clocks generally use microwaves to determine the length of a second. However, research has shown that illuminating atoms with visible light can help in much more accurate counting of the second since light waves have a higher frequency.

Light-based or optical atomic clocks could potentially lose a second in 30 billion years compared to microwave-based clocks. However, to reach this accuracy, the clocks need to be high-precision, i.e., able to measure tiny fractions of the second.

Improving the precision of the atomic clock

Instead of using a beam of visible light, the researchers at JILA used a web of light, also known as an optical lattice, to measure tens of thousands of atoms simultaneously. This gave the atomic clock more data to arrive at a precise measurement of the second.

Although the optical lattice approach has been used before, JILA researchers used a relatively gentler approach to make their measurements. This aided in reducing two sources of error: the laser itself measuring the atoms and the effect of the atoms bumping into each other when they are packed tightly together, the press release said.

Measuring effects of relativity and beyond

According to Einstein’s theory of general relativity, gravity affects time. A stronger gravitational field results in a slower passage of time. The JILA-developed clock is sensitive enough to detect the effect of gravity on timekeeping at a submillimeter scale.

Researchers observed the subtle changes in the flow of time due to gravity, when the clock was raised or lowered even small distances.

“It’s pushing the boundaries of what’s possible with timekeeping,” said Jun Ye, a physicist at JILA and NIST. However, the gains of the clock design go beyond these measurements and into the quantum realm.

Quantum computers manipulate the properties of atoms and molecules to perform complex computations. Since the JILA clock can make precise measurements, the researchers plan to use it in the microscopic realm, 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 can also help scientists keep precise time over extremely large distances in space.  “If we want to land a spacecraft on Mars with pinpoint accuracy, we’re going to need clocks that are orders of magnitude more precise than what we have today in GPS,” added Ye in the press release .

“We’re exploring the frontiers of measurement science, when you can measure things with this level of precision, you start to see phenomena that we’ve only been able to theorize about until now,” Ye concluded.

JILA is a joint institute between the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder.

The research findings will be published in the journal Physical Review Letters .