Bose-Einstein condensation.

Bose-Einstein condensation is a phenomenon that occurs in a gas when quantum-mechanical effects extend across macroscopic distances to convert microscopic, isolated atoms, with integer spins, into a single quantum system. Predicted in 1924 by Albert Einstein, the effect occurs at extremely low temperatures, when the quantum wavelengths of the individual atoms extend to cover one another. The atoms then condense from an atomic gas into a giant quantum system analogous, in solids and liquids, to superconductors and superfluids.