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Scientists Make the Coldest Object on Earth

Researchers cooled a tiny aluminum drum almost to absolute zero and think they can go even further

It can get much, much colder than this. (TothGaborGyula via iStock)
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Though winter often seems like the coldest cold, temperatures can drop much lower. That is, until you hit absolute zero, reports Sarah Kaplan at The Washington Post. This is the point when all motion of atoms that make up an object stop moving—a chilling 0 Kelvin or -459.67 Fahrenheit.

Researchers have tried for decades to reach absolute zero, which is thought to be impossible to ever attain. But recently the scientists at the National Institutes of Standards (NIST) in Boulder, Colorado got closer than scientists ever have. According to a press release, researchers believe that their new technique may actually allow them to reach that fabled point.

“The results were a complete surprise to experts in the field,” José Aumentado, co-author of a paper on the technique recently published in the journal Nature says in the press release. “It’s a very elegant experiment that will certainly have a lot of impact.”

Though scientists have previously brought individual atoms to absolute zero and even lower, this latest study documents the coldest complex object to date. The details are pretty technical, but Kaplan explains that in a process called sideband cooling, researchers used lasers to frost over a tiny aluminum drum, just 20 micrometers across and 100 nanometers thick.

"This may seem counterintuitive," Kaplan writes. "[W]e're used to light warming things up, like the sun—but in sideband cooling, the carefully calibrated angle and frequency of the light allows photons to snatch energy from the atoms as they interact."

Using this method, researchers had previously reduced the motion of the drum to what's known as quantum "ground state"—which is just one-third of a quantum of energy. But Teufel had an inkling it could get colder. "The limit of how cold you can make things by shining light on them was the bottleneck that was keeping people from getting colder and colder," Teufel tells Kaplan. "The question was, is it fundamental or could we actually get colder?"

Cold Drum
The aluminum drum at NIST (NIST)

Though the lasers cooled the object, some noise in the lasers provided tiny "kicks" of heat, Teufel explains in the press release. So Teufel and his colleagues “squeezed” the light, lining the tiny packets of energy in the laser up even tighter to cool the drum without adding energy back into the system. This allowed them to cool the drum to one fifth of a quantum, and they believe that with further refinements this system might enable them to cool the drum to absolute zero.

Such extreme cooling is not just a parlor trick: It has real world applications, too. “The colder you can get the drum, the better it is for any application,” Teufel says in the press release. “Sensors would become more sensitive. You can store information longer. If you were using it in a quantum computer, then you would compute without distortion, and you would actually get the answer you want.”

Cooling the drum could also help scientists observe some of the mysteries of quantum mechanics first hand. “I think we’re in an extremely exciting time where this technology we have available gives us access to things people have been talking about as thought experiments for decades,” Teufel tells Ian Johnston at The Independent. “Just now what’s exciting is we can go into the laboratory and actually witness these quantum effects.”

Teufel tells Johnston that cooling the drum to absolute zero, in which only quantum energy remains, would allow scientists to observe some of the weirder aspects of quantum theory. For instance, the drum, if it were scaled up, could be used to teleport visible objects. The research could also help researchers bridge the gap of understand between the point at which quantum physics, which governs very small particles, seems to stop working and more classical physics, governing large objects like stars and planets, begins to take over.

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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