Chinese physicists made a cold atomic clock in space

Saying time accurately is important; it lets you get up in the morning and coordinates everything from air travel to GPS. And if you do it well enough, you can even use it to navigate in the space.

But saying time is also a major technical challenge. Every clock in the world is inaccurate to some degree. Whatever technology your wristwatch uses to mark the future in the past, these measurements will be imperfectly measured. From time to time, a split second is lost. Even atomic clocks – which measure time by observing the ultra-precise oscillations of individual atoms and are the official timekeepers of the world – are imperfect, which is why researchers are still trying to build one that is little more precise. And now, for the first time, a team of Chinese researchers has discovered how to operate one of the most accurate atomic clock technologies currently available in the space.

In an article published today (July 24) in the journal Nature Communications, a team of researchers from the Institute of Optics and Fine Mechanics of Shanghai at the Academy of China Science has officially announced that it has successfully used a cold atomic clock for more than 15 months in orbit aboard the Chinese space station Tiangong-2. (The achievement was originally reported in Science magazine in September 2017, when a version of the article was published in the pre-printed arXiv journal before being peer-reviewed. and the official publication process.) [Wacky Physics: The Coolest Little Particles in Nature]

Working by laser cooling the atoms to a near absolute zero before measuring their oscillations, may be more accurate because at very low temperatures, these "ticks" are more consistent. But getting atoms at these temperatures is very difficult on Earth, let alone within the confines of a spaceship.

Cold atomic clocks measure the vibrations of atoms while they are in free fall so that they do not interact with anything else. On Earth, this requires constantly pushing an atom upward so that it can be measured as it falls through the detector.

The researchers managed to make ultra-cold atoms in free fall before, the team writes. But that meant more or less launching the experiment in the air and dropping it.

"These methods provide a microgravity environment ranging from a few seconds (drop tower, parabolic flight) to several minutes (sound rocket)" the study.

It is difficult to operate such a device in orbit, the researchers write, because it must be much smaller than its counterparts on Earth, pbad the necessary security tests to get into the space, work in Microgravity, protecting yourself from cosmic radiation – and doing all this without any quantum physicist to make adjustments if something had to go wrong.

But cold atomic clocks have certain advantages, the researchers wrote. More importantly, they can study atomic oscillations over much longer periods. In microgravity, the atom can stay in place longer, allowing a longer measurement period.

As reported by Science in 2017, researchers from the European Space Agency (ESA) said that Tiangong-2's cold atomic clock was not as accurate. could have been. But the ESA clock – which, in theory, would be more accurate – has faced delays and has never really gone back into space.

Originally published on Live Science.