June 24, 2005

J.D. Harrington/Michael Braukus
Headquarters, Washington
(Phone: 202/358-5241/1979)

Jane Platt 
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-0880) 

RELEASE: 05-163

WHIRLING ATOMS DANCE INTO PHYSICS TEXTBOOKS

NASA-funded researchers at the Massachusetts Institute of Technology, 
Cambridge, Mass., have created a new form of superfluid matter. This 
research may lead to improved superconducting materials, useful for 
energy-efficient electricity transport and better medical diagnostic 
tools.

The research marks the first time scientists have positively created a 
friction-free superfluid using a gas of fermionic atoms, atoms with 
an odd number of electrons, protons and neutrons. The breakthrough 
happened on the night of April 13.

"It's a night I won't forget. It was overwhelming to watch on our 
computers as the lithium atoms behaved in a way that no one had ever 
seen before," said Dr. Wolfgang Ketterle, a Nobel prize-winning 
physics professor at MIT who led the team of researchers. 

To accomplish this experiment, Ketterle's team cooled a gas cloud of 
lithium atoms to nearly absolute zero (about minus 459 degrees 
Fahrenheit). They used an infrared laser beam to trap the gas, then a 
green laser to spin it. 

A normal gas simply spins, but a superfluid can rotate only by forming 
quantum whirlpools. A rotating superfluid looks like Swiss cheese; 
the holes are the cores of the whirlpools. This is exactly what the 
MIT physicists observed that night.

In 1995, Ketterle and his team were among the first to create a 
Bose-Einstein condensate, composed of bosonic atoms that have an even 
number of electrons, neutrons and protons. In Bose-Einstein 
condensates, particles act as one big wave, a phenomenon predicted by 
Albert Einstein in 1925. That discovery earned Ketterle a shared 
Nobel Prize in Physics in 2001. Bose-Einstein condensates were later 
shown to be superfluids. 

The new frontier became fermions. Fermions must pair up to have an 
even number of electrons, neutrons and protons, which allows them to 
form a Bose-Einstein condensate. Breakthroughs at MIT and several 
other institutions, including Duke University, Durham, North 
Carolina, produced Bose-Einstein condensation of fermion pairs 
loosely bound as molecules, but found no concrete evidence of 
superfluidity.

Over the past two years researchers have been looking for the "smoking 
gun" for fermionic superfluidity. Despite some hints and indirect 
evidence, it was not found until this research team's discovery. 

Superconductivity is superfluidity for charged particles instead of 
atoms. High-temperature superconductivity is not fully understood, 
but the MIT observations open up opportunities to study the 
microscopic mechanisms behind this phenomenon. 

"Pairing electrons in the same way as our fermionic atoms would result 
in room-temperature superconductors," Ketterle explained. "It is a 
long way to go, but room-temperature superconductors would find many 
real-world applications, from medical diagnostics to energy 
transport," he added. Superfluid Fermi gas might also help scientists 
test ideas about other Fermi systems, like spinning neutron stars and 
the primordial soup of the early universe. 

The MIT research was supported by the National Science Foundation, the 
Office of Naval Research, the Army Research Office, and NASA's 
Fundamental Physics in Exploration Systems Mission Directorate, in 
support of the Vision for Space Exploration. NASA's Jet Propulsion 
Laboratory, Pasadena, Calif., Pasadena, manages the Fundamental 
Physics program. 

The research was published in the June 23 issue of Nature. Ketterle's 
co-authors include grad students Schirotzek, Schunck and Zwierlein, 
and former grad student Abo-Shaeer. They are all members of the 
NSF-funded MIT-Harvard Center for Ultracold Atoms.

For more information about NASA's Fundamental Physics Program on the 
Internet, visit: 

http://funphysics.jpl.nasa.gov

or 

http://spaceresearch.nasa.gov

	
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