ABSTRACT
Of the many application of lasers, the one with possibly the most dramatic impact on fundamental physics is laser cooling and trapping: the Nobel Prize for physics was awarded for laser cooling in 1997 [1]. The staggering progress achieved by laser cooling is reflected by considering a thought experiment that begins ‘take an atom. . . ’. Such an experiment was impossible to realize in practice because room temperature atoms move at supersonic speeds and, as atoms are neutral, there was no easy way to grab hold of them. Laser cooling allows one to obtain samples of atoms essentially at rest, with temperatures in the microKelvin region being routine. At such low temperatures, it becomes easy to trap or move atoms with modest electromagnetic forces [2, 3] and a whole new class of experiments previously confined to the realm of fantasy becomes possible. For example, one can throw atoms upwards and use precision spectroscopy to measure time or gravity with unprecedented accuracy. One can place atoms at a desired location on a surface creating a novel lithographic technique or place an atom just above the surface to create a qubit in a quantum information processor. One can take many atoms and cool them further by evaporation to form a Bose-Einstein condensate [4] or degenerate Fermi gas. This last development has propelled atomic and optical physics right into the heart of condensed matter physics and resulted in the award of the Nobel Prize in 2001.
