Laser cooling for quantum gases

Laser cooling exploits the physics of light scattering to cool atomic and molecular gases to close to absolute zero. It is the crucial initial step for essentially all atomic gas experiments in which Bose–Einstein condensation and, more generally, quantum degeneracy is reached. The ongoing development of laser-cooling methods has allowed more elements to be brought to quantum degeneracy, with each additional atomic species offering its own experimental opportunities. Improved methods are opening new avenues, for example, reaching Bose–Einstein condensation purely through laser cooling as well as the realization of continuous Bose–Einstein condensation. Here we review these recent innovations in laser cooling and provide an outlook on methods that may enable new ways of creating quantum gases. Laser cooling underpins the field of ultracold quantum gases. This Review surveys recent methodological advances that are pushing quantum gases into new regimes.