A periodic array produced by interference between laser beams propagating in opposite directions. The interference results in a periodic potential, and it is possible to trap atoms at the minima of this potential. Optical lattices can be formed in two or three dimensions. They have been used to study many aspects of quantum mechanics, particularly the theory of many-body systems, and as optical traps. As with lattices of atoms, diffraction of waves (including matter waves) can occur in optical lattices.