In statistical mechanics, Bose-Einstein statistics (or more colloquially B-E statistics) determines the statistical distribution of identical indistinguishable bosons over the energy states in thermal equilibrium. (Wikipedia)

Also, A Bose–Einstein condensate is a state of matter of bosons confined in an external potential and cooled to temps very near to absolute zero (Wikipedia)

state of matter of bosons confined in an external potential and cooled to temperatures very near to absolute 0.

A large fraction of the atoms collapse into the lowest quantum state of the external potential & quantum effects become apparent on a macroscopic scale.