academics & research

IU physicist shares story behind Nobel Prize research



As physicists discover the nature of exotic matter, they share their serendipitous stories behind the hard work leading to those successes.

IU Distinguished Professor of Physics Jorge José’s research in the 1970s led to this year’s Nobel Prize in Physics, which was awarded to David Thouless, Duncan Haldane and J. Michael Kosterlitz.

The prize was awarded for work on topological phase transitions, which describe how matter changes at very low temperatures.

While theories of phase transitions hold applications for building complicated computers and understanding how gases behave, José’s contribution shows the skepticism behind the science.

“We were trying to get an alternative derivation of solutions describing the physics,” José said about how his team of physicists studied topological phase transitions in 
the 1970s.

In contrast to ordinary phase transitions, such as the freezing of ice to water, topological phase transitions are low-temperature changes in configurations of fluids.

The Nobel Prize specifically went to work on the Berezinskii-Kosterlitz-Thouless, or BKT transition, which occurs in two-dimensional models.

Babak Seradjeh, associate professor of physics at IU, studies ways of applying forces to produce topological phases, similar to pushing a swing in a park.

“This is kind of different from the usual ways that people think about phases: solids, liquids, gases,” Seradjeh said. “We’re thinking about quantum systems.”

In quantum systems, topological phases are special types of matter influenced by the arrangement of particles, Seradjeh said.

“Electrons might be moving around and they have a tendency to jump from one atom to another atom and start circling around,” Seradjeh said.

The way electrons move depends on the topology, or arrangement, of the atoms, Seradjeh said.

Since the 1970s, physicists like José have made discoveries on these atomic arrangements in this area known as condensed matter physics.

Thouless and Kosterlitz laid the theoretical foundation for two-dimensional phase transitions in 1972.

“When they had the theory, they made a number of approximations and a number of people didn’t believe the theory at all,” José said about Kosterlitz’s and Thouless’ 
discovery.

Scientists doubted the discovery, believing the approximations made the discovery inaccurate, and some even wrote papers that contradicted it.

“I avoided reading their paper,” José said. “I didn’t read their paper because everyone said it was wrong.”

But, when José worked with physicists Leo Kadanoff, Scott Kirkpatrick and David Nelson, the team reproduced the results of Kosterlitz and Thouless in 1977.

“It was not my intention to prove they were right,” José said on the unexpected nature of the discovery.

The team’s discovery came through a long night of 
hard work.

“Kadanoff and I met from 6 p.m. to 10 p.m., and, at 10 p.m., he said ‘This is it.’” 
José said.

Kadanoff was onto something, José said.

“I stayed in my office until 1 a.m.,” José said. “When I came back at 9 a.m., he said, ‘I reformulated the 
whole thing.’”

Only after this confirmation, the paper by Kosterlitz and Thouless exploded with citations.

“We were not trying to prove they were right because we thought it was wrong, too,” José said, on Thouless’ and Kosterlitz’s research.

This would lead to numerous discoveries in the latter half of the 1970s, or what José calls the “mini golden years of theoretical physics.”

“These were discoveries and developments that would lead to three, four, five Nobel Prizes,” José said on the research done during this time.

In the following golden years of theoretical physics, physicists mathematically proved theories in phase transitions, such as those between liquids and gases and those for superfluids, liquids that flow without resistance.

American physicist Kenneth Wilson’s work on these phase transitions led his 1982 Nobel Prize, and José would later use Wilson’s theoretical work to study the BKT transition.

José also made sure that Soviet physicist Vadim Berezinskii, who was the first to do the physics contributing to Thouless’ and Kosterlitz’s discovery, received credit by adding “Berezinskii” to the name of the theory.

Berezinskii was unknown in the West until Kadanoff’s thesis advisor told Thouless about Berezinskii’s paper, José said.

Haldane, the third recipient of the Nobel Prize, studied magnetic atomic chains in the 1980s to discover how certain atomic magnets behaved topologically.

The decades of work since the 1970s led to the 2016 Nobel Prize, and the research since then wouldn’t have been possible without José’s role in the theory.

“The fact is after going around the loop, we came back to the same thing they did,” José said.

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