Using atoms at temperatures colder than deep space, Rice University physicists have delivered overwhelming proof for a once-scoffed-at theory that's become a hotbed for research some 40 years after it first appeared. In a paper available online in Science Express, Rice's team offers experimental evidence for a universal quantum mechanism that allows trios of particles to appear and reappear at higher energy levels in an infinite progression. The triplets, often called trimers, form in special cases where pairs cannot.

"It's such a remarkable phenomena," said team leader Randy Hulet. "There are examples, like the Borromean rings, where having a third component is crucial. Any two of the rings will unbind if the third is removed, and these trimers are similar. The particles want to bind, but no two can do it. They need the third one to make it happen."

The trimers were first predicted almost 40 years ago by theoretical physicist Vitaly Efimov. The most striking feature of Efimov's prediction was that the effect was both universal and repeating. That meant that the trimers could form from anything, be it as large as an atom or as small as a quark. And it also meant that Efimov's trimers would form repeatedly, up and down the energy scale in a stepwise fashion. Efimov, now at the University of Washington, even predicted the spacing in energy of the trimers; he said they would appear every time the binding energy increased by a factor of 22.7.
"A lot of people didn't believe him," said Hulet, Rice's Fayez Sarofim Professor of Physics and Astronomy. "That's partly because physicists can handle two-body problems quite well and many-body problems fairly well, but when there are just a few objects, like the three bodies in these Efimov trimers, there are just too many variables."

---

The above, from Phys.Org's news feed, is a wonderful breakthrough. It explains MOAB. Well, 92,5 per cent of it, anyway.



A