  Advances in light shaping for optical trapping of neutral particles have led
to the development of box traps for ultracold atoms and molecules. These traps
have allowed the creation of homogeneous quantum gases and opened new
possibilities for studies of many-body physics. They simplify the
interpretation of experimental results, provide more direct connections with
theory, and in some cases allow qualitatively new, hitherto impossible
experiments. Here we review progress in this emerging field.
