BOSE--EINSTEIN CONDENSATE

Bose-Einstein condensate

A Bose–Einstein condensate (BEC) is a state of matter of a dilute gas of bosons cooled to temperatures very close to absolute zero (that is, very near 0 K or −273.15 °C). Under such conditions, a large fraction of Bosons occupy the lowest quantum state, at which point macroscopic quantum phenomena become apparent.

This state was first predicted, generally, in 1924–25 by Satyendra Nath Bose and Albert Einstein

Satyendra Nath Bose first sent a paper to Einstein on the quantum statistics of light quanta (photons), deriving Planck's quantum radiation law without any reference to classical physics, and Einstein was impressed, translated the paper himself from English to German and submitted it. Einstein then extended Bose's ideas to matter in two other papers.The result of their efforts is the concept of a Bose gas, governed by Bose-Einstein statistics, which describes the statistical distribution of identical particles with integer spin, now called bosons. Bosons, which include the photon as well as atoms such as helium-4 (⁴He), are allowed to share a quantum state. 

Although it had been predicted for decades, the first atomic BEC was made only in 1995, when Eric Cornell and Carl Wieman of JILA, a research institution jointly operated by the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder, cooled a gas of rubidium atoms above absolute zero. Along with Wolfgang Ketterle of the Massachusetts Institute of Technology(MIT), who created a BEC with sodium atoms, these researchers received the 2001 Noble Prize for Physics. Research on BECs has expanded the understanding of quantum physics and has led to the discovery of new physical effects.

The most intriguing property of BECs is that they can slow down light. in 1998, Lene Hau of Harvard University and her colleagues slowed lighttravelling through a BEC from its speed in vacuum of 3 × 108 m/s to a mere 17 m/s or about 38 miles per hour.