Laser cooling for quantum gases

What does it mean when we say that something is extremely cold? A physicist’s answer would be: this means that atoms and molecules barely move. For several decades now, physicists have been developing techniques to create such ultracold states of matter, using lasers to bring gasses into the regime where quantum mechanics reigns. In a new ‘Insight’ issue of Nature Physics, UvA-physicists describe the developments in this nearly motionless yet very exciting world.