Press Release

Form of matter discovered in 1995 shows ability to collapse, explode

By SpaceRef Editor
July 19, 2001
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A group of Colorado physicists who made worldwide news in 1995 by creating a new
form of matter called Bose-Einstein condensate have developed a new “flavor” of the
matter that has been delivering surprise after surprise in the laboratory.

Composed of scientists from the University of Colorado at Boulder and the National
Institute of Standards and Technology in Boulder, the group created the Bose Einstein
Condensate, or BEC, in 1995 by cooling atoms of the rubiduim-87 isotope to near
absolute zero.

Led by CU-Boulder Distinguished Physics Professor Carl Wieman and NIST Senior
Scientist Eric Cornell, the team created a material that shared a quantum state and
behaved like a single “superatom.”

More recently, using the rubidium-85 isotope, the group has been “tuning” the
interactions between the BEC atoms to make them attractive or repulsive by exposing the
atoms to magnetic fields, Wieman said. To create the new BEC phenomenon, they
cooled the matter to 3 billionths of a degree above absolute zero, now the lowest
temperature ever achieved.

A paper on the subject is being published in the July 19 issue of Nature. Authers include
Wieman of CU and JILA, Cornell of JILA and NIST, associate researchers Elizabeth
Donley and Simon Cornish of CU and JILA, and CU graduate students Neil Claussen
and Jacob Roberts.

JILA is a joint institute of CU-Boulder and NIST headquartered on campus. By tinkering
with the magnetic fields, the researchers have been able to shrink the condensate,
which is followed by a tiny explosion — similar in some ways to a microscopic supernova
explosion and which Wieman’s team has dubbed a “Bosenova.” About half of the original
atoms appear to vanish during the process, he said.

“We have gotten down to the nitty-gritty science and have been able to study the behavior
of a new material by manipulating it in new and different ways,” Wieman said. The new
form of matter created in 1995 is named after Albert Einstein and Indian physicist
Satyendra Bose, who predicted its existence in 1924.

“The beauty of the newly created rubidium-85 condensate is that the interactions of the
atoms can be experimentally adjusted to be large or small and attractive or repulsive
simply by changing the strength of the magnetic field in which the atoms sit,” said
Wieman.

He said Donley and the team have been able to thoroughly investigate the condensate
behavior when the interactions suddenly are changed from being repulsive to strongly
attractive. “This is a particularly interesting regime because the physics equations that
describe the condensate do not have stable solutions under these conditions,” said
Wieman.

He likened the situation to the way the equations of gravity cannot be solved under the
conditions where the gravitational attraction is so large that a black hole can form. “In this
paper, we report the first measurements of what happens to a condensate when the
interactions suddenly are made attractive.”

The unexpected behavior included parts of the condensate shrinking down into small
clumps and a sudden explosion of atoms flying out of the condensate, spewing more
energy in one direction than another. Other observations included a fraction of the atoms
simply disappearing from sight and a small, quivering condensate left behind as a result
of the collapse, he said.

“The extensive set of measurements in this paper provides the first detailed description
of the behavior of matter in this very novel physical regime,” said Wieman. “This is
expected to generate new theoretical ideas that will explain this data and provide a
deeper understanding of BEC and quantum physics in general.”

SpaceRef staff editor.