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World's quietest gas lets physicists hear faint quantum effects

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World's quietest gas lets physicists hear faint quantum effects
> http://phys.org/news/2015-08-world-quietest-gas-physicists-faint.html

> Physicists at the University of California, Berkeley, have cooled a
> gas to the quietest state ever achieved, hoping to detect faint
> quantum effects lost in the din of colder but noisier fluids.

> While the ultracold gas's temperature - a billionth of a degree above
> absolute zero - is twice as hot as the record cold, the gas has the
> lowest entropy ever measured. Entropy is a measure of disorder or
> noise in a system; a record low temperature gas isn't necessarily the
> least noisy.

> "This 'lowest entropy' or 'lowest noise' condition means that the
> quantum gas can be used to bring forth subtle quantum mechanical
> effects which are a main target for modern research on materials and
> on many-body physics," said co-author Dan Stamper-Kurn, a UC Berkeley
> professor of physics. "When all is quiet and all is still, one might
> discern the subtle music of many-body quantum mechanics."

> The quantum gas, a so-called Bose-Einstein condensate, consisted of
> about a million rubidium atoms trapped by a beam of light, isolated
> in a vacuum and cooled to their lowest energy state. The entropy and
> temperature were so low that the researchers had to develop a new
> type of thermometer to measure them.

> While achieving extremely low temperatures may make the record books,
> UC Berkeley graduate student Ryan Olf said, what scientists aim for
> today are low-entropy states they can study to understand more
> interesting but difficult-to-study materials.

> The UC Berkeley team's ability to manipulate ultracold, low-entropy
> gases will allow them to study these quantum systems, including
> quantum magnets - potentially useful in quantum computers - and
> high-temperature superconductors. High-temperature superconductors
> are experimental materials that display superconductivity -
> electrical flow without resistance - at relatively high temperatures
> compared to the 3 or 4 degrees Celsius above absolute zero typical of
> today's conventional superconductors.

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World's quietest gas lets physicists hear faint quantum effects Sam Wormley <swormley1@gmail.com> - 2015-08-04 20:23 -0500

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