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Ketterle Wins Nobel For Work in Physics

By Eun J. Lee


The Royal Swedish Academy of Sciences named MIT Physics Professor Wolfgang Ketterle as one of the 2001 Nobel Prize laureates in Physics on Tuesday for his work in experimentally discovering Bose-Einstein condensates (BEC), a new state of matter.

Ketterle shares this honor with two MIT alumni, Eric A. Cornell PhD ’90 and Carl E. Wieman PhD ’73. Four other 2001 Nobel prize winners in the categories of Chemistry, Economics, and Medicine also have close affiliation with MIT.

“This is testimony to the excellence of students and faculty who are attracted to MIT, and to our dedication to intense work in fields of fundamental importance,” said President Charles M. Vest.

In their press release, the Swiss Academy recognized Ketterle and the two other winners “for the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates.”

“On behalf of the entire [physics] department, this is an unbelievably exciting occasion,” said physics department head and Donner Professor of Physics Marc A. Kastner.

Bose-Einstein Condensates (BEC) were first theorized by Albert Einstein and Indian physicist Satyendranath Bose in the late 1920’s.

Essentially, Einstein predicted that if a gas of certain types of atoms are cooled to a very low temperature, all the atoms will suddenly gather in the lowest possible energy state to form a new state of matter.

“The primary impact of this discovery is that it is one of the few developments in physics recently that has unified the different subfields of atomic physics and condensed matter physics,” said Professor David E. Pritchard.

The main problem that physicists had to solve in order to experimentally produce BECs was that of developing the technology to supercool atoms down to micro and nano Kelvins.

Pritchard best described the magnitude of this problem in the following synopsis: The average room temperature is about 300 Kelvins. If you decrease this temperature by a factor of ten, you reach the temperature of interstellar space. The temperature needed to produce BEC is still more than a million times less than that, where the average velocity of each atom is measured in millimeters per second.

Lecture sheds light on BECs

Ketterle gave a lecture on Thursday evening in 10-250 to an audience packed with professors, students, and other members of the MIT community.

“I’m glad to see the ‘usual’ audience at our physics colloquium,” joked Kastner in response to the large crowd.

Ketterle began his presentation by describing Bose-Einstein Condensate as “the coldest matter in the universe” which is “matter made of matter waves.”

Essentially, when BECs form, the wavelengths of these atoms begin to “step in unison.” This formation of BEC in a gas was realized in 1995 by Ketterle through the combined techniques of laser cooling, developed highly by Pritchard, and evaporative cooling through a magneto-optical trap, developed by professors Thomas J. Greytak and Daniel Kleppner. The method of forming BEC was later improved by using a “cloverleaf trap,” which is now the method by which MIT produces most of the BEC used in experiments.

At the time, Ketterle and his MIT lab were in a race to form BEC with the Boulder group scientists with whom he shares the Nobel Prize.

“The race went on, and it was the most exciting race of my lifetime,” said Ketterle.

Although the Boulder lab was the first to form BEC, Ketterle and his lab also formed BEC on September 20, 1995.

“We worked the whole night and I had to teach 8.012 the next morning,” said Ketterle.

Ketterle’s major accomplishments lay not only in forming BEC, but in researching the qualities of the condensate. Using two separate BECs which were allowed to expand into one another, he obtained very clear interference patterns which showed that the condensate contained entirely coordinated atoms. Ketterle also produced a “laser beam” using matter instead of light, which was made of a stream of small BEC drops falling under the force of gravity.

“BEC is about the creation of atoms with laserlike properties,” said Ketterle.

BEC research continues

More research is currently being conducted on BECs. “We are now able to use optical traps as a transport mechanism for BECs,” Ketterle said.

He described the practical applications of this discovery as being twofold. First, he elucidated the value of this research on its fundamental level to understand nature. Secondly, BECs are teaching scientists how to manipulate atoms with an unprecedented amount of precision, which may one day be the building blocks for fields such as nanotechnology and quantum computation.

“The field has explosively grown and it’s brimming with excitement,” said Ketterle. “I think there is more to come.”

Success has many fathers

Prior to Ketterle’s presentation, he was introduced by three other members of the physics department. The recent spotlight on Ketterle brings to light the many accomplishments and close-knit relationships between many members of the physics department faculty.

“Success has many fathers and some grandfathers,” Kleppner said. “I am happy to be a grandfather.”

“An awful lot of the route to BEC was paved here at MIT -- first by the work of [Professors] Kleppner and Greytak in evaporative cooling and also by the contributions of my group in laser cooling,” Pritchard said.

“I feel I was privileged to finish what these people have started,” Ketterle said.

Pritchard has had six proteges go on to become Nobel laureates.

“Dan [Pritchard] began the establishment of what is now a great school of atomic physics,” said Kleppner. “To me, this example of mentoring is in the very best tradition of science, teaching, and hopefully of MIT.”

Pritchard saw much potential in Ketterle when he invited him to work with him in 1990. Pritchard withdrew from the field so that Ketterle could do research in the field without a competing faculty member.

“The reason Ketterle was successful is because he’s the only scientist I’ve ever met who is ‘A+’ at everything,” Pritchard said. “Your most important A+ ability is your value as a colleague and friend,” said Pritchard to Ketterle at the end of his introduction.

“I can’t imagine anyone better suited to represent this discovery than Wolfgang, who not only has a passion for science, but can convey it beautifully,” Kastner said.

In the past 30 years, the Physics department has produced five nobel prize winners.

Seven laureates come from MIT

In total, seven of this year’s announced Nobel Prize winners have direct connections with MIT. Five of the laureates are alumni, one is a former professor, and one is a current professor.

K. Barry Sharpless was an MIT chemistry professor for 17 years until he joined Scripps Research Institute in 1990. He was chosen to share the 2001 Nobel Prize in chemistry with two other researchers. After leaving MIT, Sharpless and his wife contributed $30,000 to establish a Undergraduate Research Opportunities fund for students in organic chemistry.

Leland H. Hartwell Ph.D. ’64 shares the 2001 Nobel Prize in physiology or medicine for his discoveries of key regulators of the cell cycle. Two of the three Nobel Prize honorees in economics, George A. Akerlof and Joseph E. Stiglitz, both earned PhDs from MIT in economics in 1966.