New property of matter
PHYSICISTS AT the University of California, San Diego have for the first time observed the spontaneous production of coherence within `excitons,' the bound pairs of electrons and holes that enable semiconductors to function as novel electronic devices.
Scientists working in the emerging field of nanotechnology, believe that this newly discovered property could eventually help the development of novel computing devices according to a University of California, San Diego press release.
The findings were published in the journal Physical Review Letters.
Modern physics was born by the discovery that all particles in nature are also waves. "Coherence means that such waves are all `in sync,'" said Leonid Butov, a professor of physics at UCSD and one of the authors.
Visualising coherance
Superconductivity and lasing are examples. "A simple way to visualise coherence is to imagine cheering spectators at a stadium making `a wave'," added Michael Fogler, a co-author of the paper. "If the top rows get up and down at the same time as the bottom ones, the rows are mutually coherent. In turn, coherence is spontaneous when the cheering is done on the spectator's own initiative."
A famous example of spontaneous coherence of matter waves is the Bose-Einstein condensate.
"Excitons in such nano-structures can live a thousand or even a million times longer than in a regular bulk semiconductor," said Butov. "These long-lived excitons can be prepared in large numbers and form a high density exciton gas. But whether excitons can cool down to low temperatures before they recombine and disappear has been a key question for scientists."
Spontaneous coherence
"What we found was the emergence of spontaneous coherence in an exciton gas," added Butov. — Our Bureau
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