Bose–Einstein condensation of atomic gases

The discovery of the superfluid transition of liquid helium [1, 2] marked the first achievement of Bose–Einstein condensation in the laboratory, more than a decade after Einstein’s prediction for an ideal gas [3, 4]. Together with superconductivity, they o↵ered the first examples of macroscopic quantum phenomena and as such constituted a milestone in the history of Physics. The quest for the understanding of liquid helium superfluidity was the source of major advances in quantum many-body physics, such as the development of techniques inspired from quantum field theory and Landau’s phenomenological two-fluid model. The latter was in particular very successful for describing the hydrodynamics of this quantum liquid.