Sharpening the Features of Optical Lattices

U ltracold atomic gases offer unique opportunities to study quantum matter in a pristine, wellcontrolled environment. One general method for controlling the atoms and their interactions is to trap them in a so-called optical lattice—a periodic optical potential created by interfering laser beams. Lasers can “sculpt” such potentials with a spatial resolution determined by the laser light’s wavelength, which is typically around several hundred nanometers. Optical potentials that vary on shorter length scales could allow researchers to probe so-far inaccessible regimes of atomic interactions, but the fundamental limits posed by light diffraction challenge the realization of subwavelength lattices. Now, Yang Wang from the Joint Quantum Institute in Maryland and coworkers have managed to overcome these diffraction limits [1], creating an optical lattice with features 50 times smaller than the wavelength of the light that creates the lattice. This approach could allow quantum simulators based on coldatom lattices to tackle a broad range of quantum problems in physics and chemistry.