Science & Technology - Posted by Charlotte Hsu-Buffalo on Monday, April 2, 2012 14:47 - 0 Comments
A rarity for fermions: Collective behavior
U. BUFFALO (US) — Particles called fermions exhibit collective behavior in unexpected situations, according to new research.
Unlike boson particles, which like to act in unison with others, fermions have a mind of their own.
Different as they are, both species can show “collective” behavior—an effect similar to the wave at a baseball game, where all spectators carry out the same motion regardless of whether they like each other.
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Scientists generally believed that such collective behavior, while commonplace for bosons, only appeared in fermions moving in unison at very long wavelengths. Now, however, collective behavior has been discovered at short wavelengths in one Fermi system, helium-3.
A team led by Eckhard Krotscheck, a physicist who recently joined the University at Buffalo from the Johannes Kepler University in Linz, Austria, predicted the existence of the behavior using theoretical tools. Independently, but practically at the same time, a French team observed the collective behavior.
A paper detailing both the theoretical and experimental discoveries appeared recently in the journal Nature.
Krotscheck says the scientists’ success in developing accurate theoretical predictions lay, in part, in the fact that they focused on mathematical tools instead of trying to reproduce experiments.
“Knowing how nature ticks at a microscopic scale, we set out to develop a robust theory that was capable of dealing with a wide range of situations and systems,” Krotscheck says. “We demanded that our mathematical description is accurate for both fermions and bosons, in different dimensions, and for both coherent and incoherent excitations.”
Krotscheck’s colleagues on the study include researchers from the Institut Néel, CNRS, Université Joseph Fourier in France; the Institut Laue-Langevin in France, Oak Ridge National Laboratory; and the Institute for Theoretical Physics at Johannes Kepler University in Austria.
More news from the University at Buffalo: www.buffalo.edu/news/