Arthur Ashkin (1922–2020)

After Theodore Maiman demonstrated the laser in 1960, Ashkin worked in this new field and, with Gary Boyd, made important advances in non-linear optical devices. Since childhood, Ashkin had been fascinated by the forces due to light. In 1985, my research team, with Art and Bjorkholm, showed that light could cool atoms to less than a thousandth of a degree above absolute zero by using an 'optical molasses' created by three counter-propagating sets of laser beams. Holding atoms cooled to just above absolute zero in a single beam was analogous to trapping micrometre-sized polystyrene spheres in water at room temperature.