Department of Physics

Stanford University, Stanford, CA 94305

These are two of several newspaper articles related to Prof. Laughlin's 1998 Nobel Prize in Physics.

Wednesday, October 14, 1998

Research on the interaction of atoms and molecules won the Nobel Prize for Chemistry yesterday, and Physics prize was awarded for work involving a bizarre form of electrons. Both awards involved quantum theory and went to scientists working in the United States.

The Nobel Prize in Chemistry was awarded to Walter Kohn, 75, of the University of California at Santa Barbara and John A. Pople, 72, of Northwestern University.

Dr. Kohn was honored for his work in the 60's on mathematical analysis of bonds between atoms in molecules. Dr. Pople's work involved computer techniques for determining molecular structures. The work is used to predict chemical reactions and in designing molecules for use in medicine and other applications.

The physics prize went to Robert B. Laughlin of Stanford University, Horst L. Störmer of Columbia University and Daniel C. Tsui of Princeton University, for describing how electrons behave when they are exposed to extreme cold and strong magnetic fields. Scientists believe the work may eventually help illuminate questions about the structure of the universe.

Dr. Störmer, 49, and Dr. Tsui, 59, did their prize-winning work together at Bell Laboratories in 1982. Dr. Laughlin, 47, then their colleague at Bell Labs, described its theoretical underpinnings the next year.

All five of the new Nobel Laureates are physicists. And although all work in the United States, only Dr. Laughlin was born in this country. Dr. Kohn emigrated from Austria, Dr. Tsui was born in China, and Dr. Störmer was born in Germany. All are American citizens. Dr. Pople was born in Britain and remains a British subject.

Wednesday, October 14, 1998

Quantum theory, in its more arcane and practical guises, was the focus of the Nobel Prizes in Physics and Chemistry announced yesterday by the Royal Swedish Academy of Sciences. The three winners of the physics prize and the two winners of the chemistry award are all university professors in the United States.

Quantum theory, which has been evolving since the beginning of the century, in a mathematical framework describing the behavior of ultra-small objects, including atoms.

The chemistry prize of $978,000 will be shared by Dr. Walter Kohn, 75, and Austrian-born physicist who works at the University of California at Santa Barbara, and Dr. John A. Pople, 73, a Briton who is a mathematician at Northwestern University in Evanston, Ill.

Their achievements helped extend the mathematics of quantum mechanics to predicting specific chemical reactions and designing molecules for use in medicine and other applications.

Neither chemistry laureate is a chemist. "I don't even have a degree in chemistry," Dr. Pople said in an interview.

The physics prize, also $978,000, will be shared by Dr. Robert B. Laughlin, 48, of Stanford University, Dr. Horst L. Störmer, 49, who works at Columbia University and at Bell Laboratories in Murray Hill, N.J., and Dr. Daniel C. Tsui, 59, of Princeton University. In 1982, when they did the research for which they were honored yesterday, all three physicists were working for Bell Laboratories, which is now part of Lucent Technologies Corporation.

The Nobel committee honored the physicists for their discovery of a phenomenon called the fractional quantum Hall effect.

Their achievement culminated a series of discoveries that began in 1879, when an American college student, Edwin H. Hall, found that a magnetic field applied perpendicularly to a thin metal plate caused an electric potential to appear that was perpendicular to both the plate and the magnetic field. This became known as the Hall effect, and it is commonly used to measure the strength of magnetic fields.

In 1980, Klaus von Klitzing, a German physicist, investigated the Hall effect again and discovered that when the strength of the magnetic field increased smoothly, the change in electric potential did not occur smoothly, but in steps that were proportional to integer numbers - a hallmark of quantum mechanics. The phenomenon was name the integer quantum Hall effect, and Dr. Klitzing was awarded the 1985 Nobel Prize in Physics for its discovery.

Dr. Störmer, who was born in Germany, and Dr. Tsui, born in China, took this a step further in 1982 using an ultra-powerful magnet at the Francis Bitter National Magnet Laboratory of the Massachusetts Institute of Technology in Cambridge. Preparing their experiment at Bell Laboratories, they pioneered a technique for making a transistor sandwich from layers of gallium and arsenic. They layers in this sandwich were so thin that electron movement between them was restricted to two dimensions instead of the usual three.

Installed in the big M.I.T. magnet and chilled to near the absolute zero, their device exhibited the well-known quantum Hall effect, but with a twist: the response of the electric potential to changes in the magnetic field was not only stepwise; it occurred in thirds of a step. It was as if normal electrons, which are indivisible, had been split into thirds.

After seeing their results, Dr. Laughlin, the theorist of the group, said he framed an explanation for the effect that was "completely wrong, and which, fortunately, was rejected by the referees at the journal to which I submitted our paper."

But later, he said, the true explanation came to him. "It took about one day," he said. "Science is like that. You spend a long time in the desert, and then suddenly the truth dawns."

At a news conference at Bell Laboratories yesterday, Dr. Störmer compared the electrons undergoing the fractional quantum Hall effect to balls on a billiard table. Because of a weird quantum effect that occurs when the balls are exposed to a magnetic field about a million times stronger than that of the Earth, they interact as if they were a fluid, and "they look as if they had broken into thirds. When you take the magnetic field away, the normal electrons reappear and the one-third fractional electrons disappear.

Dr. Laughlin and Dr. Störmer agreed that the fractional quantum Hall effect was unlikely to have immediate applications.

"It's more of cosmological than practical interest at the moment," Laughlin said. "Potentially, if can help us understand the structure of the vacuum throughout the space-time of the universe.

"There are two great trends in physics: Newtonian reductionism, in which you look for the wheels and cogs that make the big mechanism work, and the opposite, in which you take little things like the equations of motion and see how they make the big mechanism work. The latter is our approach."

Dr. Laughlin said his 13-year-old son, awakened at 2 A.M. by the telephone, answered the call from the Nobel committee notifying Dr. Laughlin of the award. "Some guy calling from Sweden," the boy yelled to his father.

If some quantum effects seem more like magic than reality, quantum chemistry restores the balance.

All very small objects - molecules, atoms, subnuclear particles, photons of light - obey the rules of quantum mechanics. Quantum mechanics deals with large assemblages of particles and calculates probabilities rather than certainties. Viewed quantum mechanically, all objects are said to have "wave functions" that include all their possible conditions. For instance, it is possible, because a wave function includes all possibilities, for an object to be in two places at the same time.

Since the electrons that orbit atoms are quantum particles, the mathematics of quantum mechanics apply to them, and physicists and chemists have long known that it is theoretically possible to predict the interactions of atoms by calculating the wave functions of their orbital electrons.

In practice these calculations were originally so difficult that the method had limited use in practical chemistry.

But in the 1960's a breakthrough occurred. Dr. Kohn, working at the time at the University of California at San Diego, discovered that the total energy of an atomic or molecular system could be calculated from the density of electrons at all places within the system. Knowing the energy of the chemical system allows a scientist to calculate how it will react with another system and what its characteristics may be. Dr. Kohn's approach came to be known as the Density-Functional Theory, and it is the basis of many aspects of computational chemistry, in which the geometrical structure of molecules can be mapped and reactions predicted.

For this, Dr. Kohn shares the 1998 chemistry award with Dr. Pople, who refined computer analysis of the quantum mechanics of molecules as a powerful chemical tool.

Dr. Pople was cited by the Nobel committee for his 1970 computer program names Gaussian, which allows chemists to apply quantum calculations in making rapid, reasonably accurate estimates of molecular behavior. Improvements in the Gaussian program, the Nobel committee said, have been so dramatic that it "is now used by thousands of chemists in universities the world over."

Among the users are pharmaceutical laboratories seeking shortcuts in designing effective drugs.

In principle, Dr. Pople said in an interview, mathematics can explain all aspects of chemistry.

"The trick is tailoring the mathematics to fit," he said.