Nobel Newspaper Article

Prof. Robert B. Laughlin
Department of Physics
Stanford University, Stanford, CA 94305

This is one of several newspaper articles related to Prof. Laughlin's 1998 Nobel Prize in Physics.

Washington Post
Wednesday, 14 October 1998

Studies of Matter at Smallest Scale Yield Biggest Prizes in Science

By Curt Suplee

Researchers at five American universities won the Nobel Prizes in Physics and Chemistry yesterday for their investigations of the behavior of matter at the smallest scale.

The Royal Swedish Academy of Sciences awarded the physics prize to Robert B. Laughlin of Stanford University, Horst L. Störmer of Columbia University and Daniel C. Tsui of Princeton University for their discovery that, under certain circumstances, electrons act like weird "quasiparticles" with only a fraction of the electrical charge that an electron is supposed to have.

That work, the Nobel organization said, constitutes "a breakthrough in our understanding of quantum physics," the set of principles that describes how the fundamental units of matter and energy interact. In practical terms, it may improve understanding of micro-electronic and optical devices.

The chemistry prize went to Walter Kohn of the University of California at Santa Barbara (UCSB) and John A. Pople, a British citizen working at Northwestern University, for devising ways to calculate mathematically how chemical bonds among atoms form and change. The process is so difficult that Paul Dirac, one of the architects of quantum theory, observed in 1929 that it produced "equations much too complicated to be soluble."

But Kohn and Pople, laboring independently on different aspects of the problem, invented ingenious computational methods that now make it possible to predict many aspects of reactions and molecular structures in pharmaceuticals, climate chemistry and astronomy, among other fields. The work "opens doors to faster discoveries of new medical treatments and high-tech materials," said Joan E. Shields, chairman of the American Chemical Society.

On its face, the physics research seems to contradict one of the bedrock axioms of modern science - namely, that the electron is a truly elementary particle, with no apparent structure, no subcomponents and an unvarying electrical charge. Yet what Störmer and Tsui observed in the lab, and what Laughlin later explained in theory, were unexpected entities that were comporting themselves as if they were one-third or two-fifths or some other peculiar fraction of an electron. This made no sense, especially since the experimenters were examining the seemingly well-studied Hall effect, a phenomenon with a century-old pedigree.

In 1879, U.S. physicist Edwin Hall found that when a conductor carrying a current was placed in a magnetic field perpendicular to the current, many of the moving charged particles got shoved to one side or the other of the conductor, depending on their charge. (A similar effect is used to bend a stream of electrons to scan the screen in a TV set.) As a result, positive charges piled up on one edge of the conductor and negative charges on the other, creating an internal voltage at right angles to the main current.

For decades, it was assumed that this "Hall voltage" varied continuously with magnetic field strength. But then in 1980, German physicist Klaus von Klitzing explored the phenomenon in a conducting layer so thin that, in effect, it allowed electrons to move in only two dimensions. Working at low temperatures and with much higher magnetic fields than Hall had used, von Klitzing observed that the voltage did not vary smoothly as the field was increased, but changed in incremental steps - like moving up a staircase instead of sliding up a ramp.

That accorded nicely with one of the essential dogmas of modern physics: At its most basic level, energy is quantized; that is, it does not come in an infinitude of values, but only in discrete units called "quanta". In von Klitzing's experiments, the Hall voltage was quantized into whole-number multiples of a constant based on the size of the individual electron charge. The discovery of the "integer quantum Hall effect" garnered von Klitzing the 1985 Nobel Prize in Physics.

In 1982, Störmer and Tsui were at AT&T Bell Laboratories in New Jersey, looking at the same phenomenon, but at temperatures near absolute zero, with magnetic fields four times stronger and in high-purity materials developed by Arthur C. Gossard, now at UCSB.

To their astonishment, they found a very large number of steps, most of which were not whole-number multiples, but strange fractions such as four-sevenths or five-ninths. Soon thereafter, Laughlin offered a controversial explanation: The electrons were combining with bits of the magnetic field energy to condense into fluid-like conglomerates, or quasiparticles, with many different fractional charges.

This remained a suspect hypothesis until last year, when separate teams in Israel and France found that the particles actually exist. Many experts had expected that the research was Nobel material, but Laughlin said yesterday the he went "completely bananas" at the news, according to the Associated Press.

The chemistry prize, too, involved quantum aspects of matter. Historically, chemistry has been an experimental science. That is, to see the various forms in which different elements might combine, chemists usually just mixed them up, or broke them apart, and analyzed the results. But since the 1920s, with the advent of quantum mechanics, scientists have known that atoms and their electrons combine and interact according to mathematically describable rules. So in theory, at least, it should be possible to predict the bond structure of a chemical compound, or the shape of a molecule, or the dynamics of a chemical reaction from first principles without having to resort to beakers and test tubes.

Unfortunately, the quantum-mechanical equations are so difficult, and the number of variables so enormous (each electron, after all, influences every other one - and each atom affects the quantum condition of each of its neighbors) that in practice it was simply impossible to solve them.

Then in the 1960s, Kohn created a method called "density-functional theory" that allowed scientists to used simplifying approximations to determine the interactions of many electrons in very large molecules. A few years later, Pople devised the first version of a computerized system that would simulate the shape of a molecule or the quality of a reaction from the data about the constituent atoms or type of chemical activity desired.

"Finally, we were able to go into the office and sit in front of a computer" to predict the chemical outcome, "rather than go into the laboratory and start mixing some things together," said physical chemist Geraldine Richmond of the University of Oregon. The result, she said, "really marries the fundamentals of physics and chemistry."