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MIT physicist shares 2001 Nobel Prize in physics

Wolfgang Ketterle
Wolfgang Ketterle
Photo / Donna Coveney

CAMBRIDGE, Mass. -- MIT physics professor Wolfgang Ketterle and two MIT alumni share the 2001 Nobel Prize in Physics for causing atoms to sing in unison, thus discovering a new state of matter -- the Bose-Einstein condensate (BEC).

Ketterle, 43; Eric A. Cornell, 39, a 1990 MIT Ph.D. recipient and now a senior scientist at the National Institute of Standards and Technology (NIST) in Boulder, Colo.; and Carl E. Wieman, 50, a 1973 MIT physics graduate and a physics professor at the University of Colorado at Boulder, are the three laureates.

According to the Royal Swedish Academy of Sciences, the three are recognized "for the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates."

In other Nobel news, on Monday, Leland H. Hartwell, MIT PhD 1964, shared the 2001 Nobel Prize in physiology or medicine for discoveries of key regulators of the cell cycle.

Ketterle was among the very first scientists to observe the BEC phenomenon in 1995, and realized the first atom laser in 1997.


"I am proud to be at MIT and proud to have such wonderful mentors," said Ketterle, John D. MacArthur Professor of Physics, associated with MIT's Research Laboratory of Electronicsand the National Science Foundation MIT-Harvard Center for Ultracold Atoms. "I am the youngest of three MIT faculty members who pioneered this field in the late 1970s and early 1980s. I am privileged to finish what they had started.

"This is a strange moment for me," he said. "This award is not only for a person but really recognizes atomic physics at MIT."

"Wolfgang has remarkable qualities," said MIT physics professor Daniel Kleppner, longtime colleague and friend. "As a scientist, Wolfgang has this incredible ability to define a vision and to focus his resources. Wolfgang is a superb scientist, a superb teacher and a superb colleague. He is wonderful at everything."

About Kleppner, Ketterle said, "I looked up to him and learned from him."

Ketterle joined MIT as a postdoctoral associate in 1990 under MIT Professor of Physics David E. Pritchard, a pioneer in atom trapping, atom optics and atom interferometry. When Ketterle arrived at MIT, Kleppner, Lester Wolfe Professor of Physics, and physics Professor Thomas J. Greytak had undertaken the goal of trying to see a Bose-Einstein condensate in an atomic gas.

"At the time, the only strategy was using atomic hydrogen. In the early '80s, this new development in laser physics -- laser cooling -- started to grow. Dave Pritchard played a large role in that," Kleppner said.

"Meanwhile, Greytak and I were making progress with hydrogen. Nevertheless, we couldn't quite get BEC with hydrogen. In the early '90s, laser cooling opened a much more effective approach. Cornell and Wieman, who worked in my laboratory as an undergraduate at MIT, got BEC in June 1995, and a couple of months later, Wolfgang working alone got there."

Kleppner said that he feels like a grandfather of BEC. He and Greytak "eventually got BEC with atomic hydrogen and we were very pleased with that. Like most people who worked on BEC, we thought it would be an exciting development, but we had no idea how interesting it would be and the consequences of it."

Pritchard brought Ketterle to MIT and played a major role in promoting the young physicist's career. They are now collaborating on applications for BEC.

"I'm tremendously pleased because these are sort of 'my guys.' Wolfgang, of course, was my postdoc, Eric Cornell was my student, and Carl Wieman was crew on my boat for two years," Pritchard said. "I think it's wonderful science. Maybe one of the most explosive discoveries in my field ever."


According to Nobel press materials, a laser beam differs from the light from an ordinary light bulb in several ways. In the laser the light particles all have the same energy and oscillate together. To cause matter also to behave in this controlled way has long been a challenge for researchers.

In 1924, the Indian physicist Bose made important theoretical calculations regarding light particles. He sent his results to Einstein, who extended the theory to a certain type of atom.

Einstein predicted that if a gas of such atoms were cooled to a very low temperature all the atoms would suddenly gather in the lowest possible energy state. The process is similar to when drops of liquid form from a gas, hence the term condensation.

BEC was first observed in a gas by researchers at the University of Colorado at Boulder in June 1995 and in September by Professor Ketterle's group at MIT. BECs form when atoms are cooled to around one-millionth of a degree Kelvin, or more than a million times colder than interstellar space.

At such low temperatures, the atomic matter waves overlap and the atoms lose their individual identities. They essentially march in lockstep as a single giant matter wave displaying uniform behavior. In contrast, atoms in an ordinary gas flit around independently.

Ketterle's group explored new properties of this novel form of matter. Using two separate BECs that were allowed to expand into one another, he obtained very clear interference patterns, i.e. the type of pattern that forms on the surface of water when two stones are thrown in at the same time. This experiment showed that the condensate contained entirely coordinated atoms marching in lockstep.

Ketterle also produced a stream of small "BEC drops" which fell under the force of gravity. This can be considered as a primitive "atom laser beam" using matter instead of light.

This new control of matter may bring revolutionary applications in precision measurement, nanotechnology and possibly quantum computation.

Ketterle's group is now working on novel methods to cool, trap and manipulate atoms with the goal of exploring novel aspects of ultracold atomic matter. He and Pritchard co-invented the Dark SPOT trap, which combined with laser cooling and evaporative cooling, became key techniques to obtain Bose-Einstein condensation in dilute atomic gases.

Ketterle, a German citizen, received a diploma equivalent to master's degree from the Technical University of Munich in 1982, and a Ph.D. degree from the University of Munich in 1986. After postdoctoral work at the Max-Planck Institute for Quantum Optics in Garching, at the University of Heidelberg and at MIT, he joined the physics faculty at MIT in 1993, where he is now a full professor.

Ketterle's awards include a David and Lucile Packard Fellowship (1996), the Rabi Prize of the American Physical Society (1997), the Gustav-Hertz Prize of the German physical society (1997), the Discover Magazine Award for Technological Innovation (1998), the Fritz London Prize in Low Temperature Physics (1999), the Dannie-Heineman Prize of the Academy of Sciences, Göttingen, Germany (1999), and the Benjamin Franklin Medal in Physics (2000).

Ketterle and his wife, Gaby, have three children: Jonas, 15; Johanna, 12, and Holger, 9. They live in Brookline, Mass.

Ten million Swedish kroner (around $1 million) will be shared equally by the laureates.

Fifty-one current or former members of the MIT community have won the Nobel Prize over the past 58 years. Twenty-five of them have been physicists.

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