PlanetPhysics/Bose-Einstein Condensation

Bose--Einstein Condensation (BEC)
is described as the process occurring only very close to absolute zero (for example, below 1 mK) in which a large fraction of a dilute gas of weakly interacting bosons confined in an external potential have a lowest quantum state (or states) in which their wave functions overlap; hence the name of Bose--Einstein condensate (BEC) attributed to such a system of supercooled/ultracold, weakly interacting bosons with overlapping wave functions.

The original theoretical paper was published in 1925 in \emph{Zeitschrift fur Physik} by Satyendra Nath Bose in the German translation of Albert Einstein, and followed in a few theoretical papers by Einstein himself. Recently, there have been several experimental claims reported to have observed BECs in alkali metal gases at very low temperatures (see the following selected bibliography).

For a general introduction to BECs there is also available a related paper in PDF format.

Bose-Einstein condensation in the alkali gases
A fundamental theoretical paper on this subject is: "Bose-Einstein condensation in the alkali gases: Some fundamental concepts" [Rev. Mod. Phys. 73, 307 (2001)], by Anthony J. Leggett.