News from
PRINCETON UNIVERSITY
Office of Communications
Stanhope Hall
Princeton, New Jersey 08544-5264
Telephone 609-258-3601; Fax 609-258-1301Contact: Mary Caffrey 609/258-3601
Date: October 13, 1998
Daniel C. Tsui To Share 1998 Nobel Prize in Physics
Princeton, N.J. -- Daniel Chee Tsui, Arthur Legrand Doty Professor of Electrical Engineering, on Tuesday has won the 1998 Nobel Prize in Physics for his 1982 discovery with co-winner Horst L. Stormer, now of Columbia University, of the fractional quantum Hall effect. A third co-winner, Robert B. Laughlin, explained their result the following year. The experiments by Tsui and Stormer led to Laughlin's finding that the electrons in a powerful magnetic field can form a quantum fluid, in which "parts" of an electron can be identified.
Tsui's work stems from a 1879 finding by a student, Edwin H. Hall, who discovered a pattern in the flow of electric current when a gold plate is placed in a magnetic field at right angles to its surface. The current flowing along the plate would drop at right angles. This phenomenon, termed the Hall effect, can be used to determine the density of charge carriers in conductors and semi-conductors and is a standard tool in physics laboratories.
In Hall's day, such experiments were performed at room temperature with moderate magnetic fields. By the 1970s, researchers could perform experiments at extremely low temperatures, with very powerful magnetic fields. The 1980 experiment by Klaus von Klitzing found that the Hall effect in the semiconductor silicon does not behave in a linear fashion, but instead creates "steps" along the strength of the magnetic field (von Klitzig won the 1985 Nobel Prize for this discovery).
Tsui and Stormer, then at Bell Laboratories in Murray Hill, New Jersey, performed experiments on the quantum Hall effect in the semiconductor gallium arsenide, using even lower temperatures and more powerful magnetic fields. To do so, they created a unique environment, a trap in which to restrain electrons on a two-dimensional plane. This was done by sandwiching two dissimilar semiconductor wafers--gallium arsenide on one side and gallium aluminum arsenide on the other. Electrons accumulated at the interface between the two semiconductors and were tightly confined. Next, the researchers cooled the electron trap down to a tenth of a degree above absolute zero.
To their surprise, Tsui and Stormer found that the next step in the Hall resistance was three times higher than von Klitzing's highest recorded step. Later, Tsui and Stormer found more steps, which initially could not be explained. The heights of the new steps could be expressed with the same constant used in earlier work, but were now divided by different fractions -- thus, the term fractional quantum Hall effect. This would be impossible, since electrons cannot have fractional charges. Laughlin later determined that the magnetic field had created "holes" in the two-dimensional sheet of electrons. Called vortices, these were similar to a whirlpool in a lake; in the absence of water, the vortices represent an absence of charge.
The discovery of apparently fractional electron charge opened a new era in the study of many-body phenomena. It has had impact on many branches of physics. Researchers around the world continue to make new discoveries that spring from the fractional quantum Hall effect.
Born in Henan, China, in 1939, Tsui came to the United States in 1958 to enter Augustana College, Rock Island, Illinois, from which he graduated with Phi Beta Kappa honors in 1961. After earning his Ph.D. in physics at the University of Chicago in 1967, Tsui did a year of postdoctoral research at Chicago before joining Bell Labs in 1968.
Tsui joined the Princeton faculty in 1982. His is an elected member of the National Academy of Sciences, a fellow of the American Association for the Advancement of Sciences, a fellow in the American Physical Society, and a recipient of the 1984 Oliver Buckley Condensed Matter Physics Prize of the American Physical Society. Earlier this year, he was honored with the Benjamin Franklin Medal in Physics.
Tsui lives in Princeton with his wife, Linda. He is the 29th winner of the Nobel Prize associated with Princeton University, and the 18th person affiliated with Princeton to win the prize in physics.
More information is available at the Royal Swedish Academy of Sciences
http://www.nobel.se/announcement-98/physics98.htmlDaniel C. Tsui bio
http://www.princeton.edu/pr/news/98/q4/1013-tsuibio.htmPicture of Daniel C. Tsui available at
http://www.princeton.edu/pr/pictures/98/index.htmlComputer graphic visualizing the Laughlin wave function for the nu=1/3 FQHE state.
http://www.bell-labs.com/new/gallery/fqhe.htmlSee also, April 24, 1998 press release
Daniel Tsui receives Benjamin Franklin Medal in Physics
http://www.princeton.edu/pr/news/98/q2/0424-tsui.html