A state formed by the condensation of a large number of bosons into a single quantum state at sufficiently low temperature. This phenomenon was predicted by Albert Einstein in his 1924–25 work on extending the earlier work of Satyendra Nath Bose (1894–1974) on quantum statistics. In 1938 Fritz London suggested that superfluidity is associated with a Bose–Einstein condensate of helium atoms. Although this suggestion is correct, a quantitative theory of superfluidity is more complicated than Einstein’s work of 1925; whereas Einstein was concerned with an ideal gas of bosons, helium atoms interact strongly. In 1995 a Bose–Einstein condensate was formed by trapping rubidium atoms at a temperature very close to absolute zero.