Robert Laughlin wins Nobel Prize in physics
Laughlin shares Nobel Prize; four in a row for physics.
Within hours of getting a pre-dawn call from the Royal Swedish Academy of Science, the fourth Stanford professor to win the Nobel Prize in physics in as many years was using the award as a forum for public support of research.
Robert B. Laughlin, professor of physics and applied physics and the Anne T. and Robert M. Bass Professor in the School of Humanities and Sciences, said he wants the public to understand that nature is a wonderful thing that has many surprises. He also wants people to know that providing tax money to scientists to enable them to make fundamental discoveries about nature is vital.
“I owe a debt of gratitude to the taxpayers in my parents’ generation,” Laughlin told a roomful of reporters and well-wishers, including his mother, wife and son, at a news conference Oct. 13 in Tresidder Union. “I accuse my generation of not living up to their responsibility to support basic research for future generations.”
Laughlin shares the 1998 Nobel award with Horst L. Störmer, a professor at Columbia University and Bell Laboratories, and Daniel C. Tsui, a professor at Princeton University. All three scientists worked together at AT&T’s Bell Laboratories in the early 1980s.
In a 1982 experiment, Störmer and Tsui discovered that the electrons in a semiconductor could be forced to behave like a liquid made of quasi-particles, with only one-third of the electrical charge of individual electrons. That was something no one had even dreamed was possible.
Although it is unlikely the phenomenon – known as the fractional quantum Hall effect – will ever have any practical applications, Laughlin said it has important cosmological implications.
When he was pressed to expand on its significance, Laughlin turned on the professorial charm.
“You have ordinary particles, obeying ordinary quantum mechanical laws, in ordinary conditions, that behave in unprecedented ways,” he said.
“There are new things everywhere, if only we have eyes to see them. It is a mistake to think that, just because you know the microscopic rules, you know everything.”
In what has become an autumnal event on the Stanford campus, Laughlin faced a room crammed with reporters, TV cameras, Nobel laureates, colleagues, friends and family. He expressed his gratitude for the public support that he said has made his career possible.
“The results being awarded today are the result of careful investments made by people in the previous generation,” Laughlin said.
SLAC physicist Martin Perl was awarded the Nobel Prize in physics in 1995, and Stanford’s Douglas Osheroff and Steven Chu were the recipients in 1996 and 1997. Both Laughlin and Chu have joint appointments in the departments of physics and applied physics, and both were recruited to Stanford as a result of the joint efforts of Alexander Fetter, then chair of physics, and Malcolm Beasley, then chair of applied physics and now dean of the School of Humanities and Sciences.
Stanford President Gerhard Casper praised the cooperation Fetter and Beasley demonstrated, noting that they “overcame the traditional splits between the two departments, and got together to recruit top people like Robert Laughlin.”
The Nobel laureate accepted the kudos with characteristic self-deprecating humor.
“I’ve made a couple of discoveries in my time, and let me tell you, it ain’t easy,” he said to laughter. “It’s much easier to make discoveries that aren’t real, that are wrong.”
Earlier that morning, when the call Laughlin said “every scientist hopes for” had come, the telephone in the Laughlins’ bedroom was not working. So it was their 13-year-old son, Todd, who answered it on his own Mickey Mouse phone.
“He came into our room, woke me up, and said, ‘Dad, there’s some guy from Sweden on the phone who wants to talk to you,'” Laughlin said.
The new Nobel laureate contended that he took the news calmly, but also acknowledged that his wife accused him of screaming after he hung up.
Laughlin’s mother, who rushed to his campus home after hearing the news, told him, “I never thought it would happen. I thought it was just your childhood dream.”
As reporters and television crews also began to arrive at his campus home in the early hours of what would become a long and memorable day, Laughlin took the attention in good-natured stride.
“This reminds me of a play I saw once, where more and more people kept coming into this little room.”
He answered endless questions from reporters throughout the day and at one point let slip that a particle he has studied, called the anyon, once ended up in an episode of the cult science-fiction television series, Star Trek. In the show, the Starship Enterprise is shot with a beam of anyons, but escapes unharmed because the anyons don’t have any physical effect.
At a celebratory party on the lawn outside the Varian physics building later in the afternoon that was fueled by 24 bottles of champagne, Laughlin was hailed by colleagues. Chu, last year’s Nobel winner in physics, picked up a piece of curled eucalyptus bark from the ground and handed it to Laughlin with mock solemnity, saying that he wanted to “pass the baton.”
“Let this be the standard for the rest of the faculty,” Chu added.
“Steve is right,” Laughlin shot back. “I’d love to give this to one of you.”
Margaret Martin, Laughlin’s younger sister, reminisced about how he used to build things out of junk in the garage. Sometimes he melted the wrong chemicals and ended up in the hospital with burns. And once he built a television, she said.
“He also took the vacuum apart, just before someone was going to use it,” Martin recalled. “But … he got it all back together again.”
That early experimentation may have provided the impetus that nudged Laughlin into a physics career.
Störmer and Tsui discovered the bizarre effect while applying strong magnetic fields to semiconducting material cooled to extremely low temperatures and then measuring what happens to the electrons flowing through it.
Their experiment was based on the Hall effect that was discovered in 1879 and is now a standard tool used in laboratories around the world to measure the density of electrical charges in various conducting and semiconducting materials. In 1980, the German physicist Klaus von Klitzing discovered that under certain conditions the Hall effect does not vary in a continuous fashion, but varies “stepwise” with the strength of the magnetic field. In technical terms, the effect exhibited quantum properties.
In 1982, Störmer and Tsui decided to push this effect to its limits by applying extremely strong magnetic fields. They hoped to force the electrons to “crystallize,” but found the fractionally charged quantum fluid instead.
“They pushed the effect into a regime where it shouldn’t exist,” Laughlin said of Störmer and Tsui. “The result was a quantum state without any precedent in physics.”
When they got the effect, Störmer and Tsui knew that they had discovered something extremely important, but it was left to Laughlin to explain it. “When I saw their data I knew that they had found a fractional charge,” Laughlin recalled. So he began writing down equations to see if he could explain the effect using quantum dynamics, the rules that describe the motion of subatomic particles.
“Actually, my first attempt was wrong,” he said. “Fortunately, a referee bounced the original paper back to me. So I thought about it some more and came up with a better explanation.”
According to the Nobel Foundation, “Through theoretical analysis [Laughlin] showed that the electrons in a powerful magnetic field can condense to form a kind of quantum fluid related to the quantum fluids that occur in superconductivity and in liquid helium. What makes these fluids particularly important for researchers is that events in a drop of quantum fluid can afford more profound insights into the general inner structure and dynamics of matter.”
Laughlin argues that the effect is an important clue to the rules that regulate the universe. Our understanding of the universe is based on an amalgam of experimental results and physical analogies. Without the experiments, he said, there is insufficient information to construct the analogies. So, said Laughlin, the fractional quantum Hall effect is a breakthrough because it proves that the ordinary laws of quantum mechanics can do things that we cannot anticipate.
The discovery may provide an important insight into the vacuum state, the fundamental unit of space-time. In classical physics, a vacuum is the absence of all matter. But experiments with high-energy particle accelerators conducted since the end of World War II paint a much different picture. Although it appears empty, the vacuum state is full of all kinds of matter with strange properties.
“Vacuum is something like a pane of window glass,” Laughlin said. “It is perfectly transparent, but when you hit it hard enough, you get matter, the stuff it is made from, coming out.
“There is a group of us who are very interested in understanding what this stuff is.”
The fractional quantum Hall effect suggests that the strange properties of vacuum may result from the collective behavior of particles operating under ordinary quantum dynamics, rather than consisting of fundamentally different kinds of particles or new laws.
Laughlin also sees some striking similarities between the fractional quantum Hall effect and high-temperature superconductivity, which he has been studying since he came to Stanford in 1985.
“In both cases you have groups of electrons behaving in an entirely unanticipated manner,” he said.
The case of superconductivity is more complicated, however, because scientists must disentangle collective effects from other important factors.
At the news conference, Laughlin noted that AT&T, IBM and Xerox were the three companies that once supported research in basic physics. But all have pulled out due to stockholder pressure. More recently, Lucent Technologies has begun trying to put back together what it had disassembled.
“So the ideal is still there,” Laughlin said.
In contrast to the corporate labs, Laughlin said, university research is highly political because of the involvement of the government. He added that federal officials are “impossible to work with.”
“They are control freaks,” he said. “They would not have supported the experiments that are being recognized by the award being given today.”