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Bose Einstein condensate(boseeinsteincondensate,boseeinstein condensate,bose einsteincondensate)A Bose-Einstein condensate is a gaseous superfluid phase formed by atoms cooled to temperatures very near to absolute zero . The first such condensate was produced by Eric Cornell and Carl Wieman in 1995 , using a gas of rubidium atoms cooled toone twenty-billionth of a Kelvin . Under such conditions, a large fraction of the atomscollapse into the lowest quantum state , producing a superfluid . The collapse of the atoms into a single quantum state is known as Bose condensation or Bose-Einsteincondensation. This phenomenon was predicted in the 1920s by Satyendra Nath Bose and Albert Einstein , based on Bose's work on the statistical mechanics of photons , as formalized andgeneralized by Einstein. The result of their efforts is the Bose Einstein statistics , an equation describing the statistical distribution of certain types of identical particles now known as bosons . Bosonic particles, which include the photon as well as atoms such as helium-4 , are allowed to quantum statess with each other.Einstein speculated that cooling bosonic atoms to a certain very low temperature would cause them to fall (or "condense") intothe lowest accessible quantum state, resulting in a new form of matter. Bose-Einstein condensation is responsible for the superfluid phase of helium-4 ,discovered in 1938 by Pyotr Kapitsa , John Allen and DonMisener . In fact, superfluid helium displays many properties in common with the gaseous Bose-Einstein condensates, includingdissipationless flow, the suppression of scattering by light, and the existence of quantized vortices . The main difference between the two is that the former is a liquid , while the latter is a gas . The first Bose-Einstein condensate was created by Cornell and Wieman at JILA on June 5 , 1995 . They cooled a dilute vapor consisting of approximately 2000 rubidium atoms to one twenty-billionth of aKelvin, the lowest temperature ever achieved at that time, using a combination of laser cooling (a technique that won its inventors StevenChu , Claude Cohen-Tannoudji , and William D. Phillips the 1997 Nobel Prize in Physics ) and magneticevaporative cooling . Cornell, Wieman and Wolfgang Ketterle won the 2001 Nobel Prize for this achievement. In 2003 , teams surrounding Rudolf Grimm at the University of Innsbruck in Austria and Deborah S. Jin at the University of Colorado at Boulder in the USA showed that Bose-Einstein condensates could also be formed from molecules. Bose-Einstein condensates are extremely fragile. The slightest interaction with the outside world can be enough to warm thempast the condensation threshold, causing them to break back down into individual atoms again; it will likely be some time beforeany practical applications are developed for them. However, several interesting properties have already been observed inexperiments. Bose-Einstein condensates can be made to have an extremely high gradient in the optical densities , resulting in extremely low measured speed of light within it; some condensateshave slowed beams of light down to mere meters per second, slower than a human can move on a bicycle . A rotating Bose-Einstein condensate could be used as a model black hole , allowing light to enter but not to escape. Condensates could also be used to "freeze" pulses oflight, to be released again when the condensate breaks down. Research in this field is still young and ongoing. See alsoExternal linksReferences
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