Scientists see fireworks from atoms at ultra-low temperatures

November 7, 2017 by Louise Lerner, University of Chicago
Jets of atoms shoot off together like fireworks from a central disc in a new quantum phenomenon discovered by UChicago scientists (color added for illustration). Credit: Cheng et al./University of Chicago

Scientists aren't normally treated to fireworks when they discover something about the universe. But a team of University of Chicago researchers found a show waiting for them at the atomic level—along with a new form of quantum behavior.

"This is a very fundamental behavior that we have never been seen before; it was a great surprise to us," said study author and professor of physics Cheng Chin. Published Nov. 6 in Nature, the research details a curious phenomenon—seen in what was thought to be a well-understood system—that may someday be useful in quantum technology applications.

Chin's lab studies what happens to particles called bosons in a special state called a Bose-Einstein condensate. When cooled down to temperatures near absolute zero, bosons will all condense into the same . Researchers applied a magnetic field, jostling the atoms, and they began to collide—sending some flying out of the condensate. But rather than a uniform field of random ejections, they saw bright jets of atoms shooting together from the rim of the disk, like miniature fireworks.

"If you'd asked almost anyone to predict what would happen, they would have said that these collisions would just send atoms flying off in random directions," said postdoctoral fellow Logan Clark, the first author of the study; he and co-author and postdoctoral fellow Anita Gaj were the first to see the phenomenon. "But what we see instead are thousands of bosons bunching together to leave in the same direction."

"It's like people forming a consensus and leaving in groups," Chin said.

Credit: Cheng et al/University of Chicago

The tiny jets may show up in other systems, researchers said—and understanding them may help shed light on the underlying physics of other .

Moreover, the jets, like other new quantum behaviors, may be of interest in technology. "For example, if you sent a particular atom in one direction, then a bunch more would follow in that same direction, which would help you amplify small signals in the microscopic world," Clark said.

Since there's energy delivered to the system and the particles are not at their ground states, it falls under the category of a particularly hot area of quantum engineering research called "driven" quantum systems, the authors said. The physics of systems in these quantum states is not well understood, but essential for engineering useful technologies.

However, Bose-Einstein condensates are a generally well-studied area, so they were excited to see a never-before-documented behavior, the scientists said.

"If you see something crazy in this simple experiment, it makes you wonder what else is out there," said graduate student Lei Feng, also a co-author.

Explore further: Bose-Einstein condensates miscibility properties reveal surprises

More information: Logan W. Clark et al, Collective emission of matter-wave jets from driven Bose–Einstein condensates, Nature (2017). DOI: 10.1038/nature24272

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5 / 5 (1) Nov 07, 2017
Pilot-Wave theory perhaps being the guide to cause many particles to follow with the same momentum vector. Before I get whipped and sent to the corner of the room for suggesting Pilot-Wave theory, the idea does have similarities with its legit cousin, Quantum Field Theory.
5 / 5 (2) Nov 07, 2017
@big_harry_jimbo, I doubt most people reading this stuff would send you to the corner for suggesting Pilot-Wave theory since they have no idea what it is. Whipping is another issue. Most critics belong in that corner, and bleeding, for that very reason - not knowing enough reality. And let's not forget that Schrödinger's cat is still lurking around somewhere.....or not!

Still, it should not surprise us too much that streams of matter would flow from jostling a Bose-Einstein condensate since one expects the condensate to have fairly high density. Perhaps it depends on what is condensed and jostled. Might relate to some cohesive interaction(s). I should think individual particles flying off in all directions would be less likely. As I work at the biomolecular level, I am hardly an expert at jostling Bose-Einstein condensates. Biochemistry has some things in common with Pilot-Wave theory by the by. I might end up in the corner too. But you are the whipping boy for starting all th
5 / 5 (2) Nov 07, 2017
@dfjohnsonphd - I would be quite surprised if the density of the condensate was very high. Normally, these kinds of experiments deal with atom counts of under 1 million. Putting a million atoms in almost any conceivable experimental setup leaves a LOT of space between atoms.

In addition, remember we are talking about bosons in this experiment. Bosons usually act quite independently of each other. Finding correlated behavior is astonishing.
5 / 5 (1) Nov 07, 2017
I certainly agree that the boson condensate is likely very different. But if memory serves me correctly, B-E condensates in general take on the characteristics of a single atom (or particle) rather than the aggregate form, suggesting an inherent cohesiveness. Perhaps I am being overly simplistic and thinking of the lithium quenching shown to result in attractive condensates with higher densities, and those from helium-4, which are superfluids, where the interactions between the atoms are relatively strong. For me, observing anything in these experiments that is reproducible and suggestive of a unique state of matter is astonishing.
5 / 5 (1) Nov 07, 2017
It might be significant to point out that B-E condensates are suggested to represent a new state, or perhaps states, of matter. And while they may have started as "gases", these "B-E gases" may not have the same properties as those of "standard" gases. We may need to preface the form of gas as these experiments reveal more about their physical properties. It certainly looks like a field of study in its infancy, one that is ripe for many degrees and publications. It looks like biochemistry before they discovered DNA -> RNA -> protein.
5 / 5 (1) Nov 08, 2017
From 16 years ago, the "Bosenova" https://www.nist....bosenova
not rated yet Nov 10, 2017
Could it be used as a workaround for the Heissemberg uncertainty principle ? I mean, if one photon hits the condensate and can be amplified the origin of the jet could give us its position , and the average momentum of the jet could give us its momentum vector. If that is the case it could have very interesting applications , for example we could use it to measure both position and momentum from incoming photons in a telescope and directly image exoplanets. Currently only very high energy photons can be amplified with particle showers to get both the "pixel" were they hit and the frequency and direction where they come from (momentum), but could this technology do it within low energy photons as required for this application ?

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