24 June 2016
Vol 352, Issue 6293

About The Cover

Cover image expansion

COVER Artist's interpretation of ultracold atoms trapped in a disordered two-dimensional lattice formed by laser light. Researchers observed a sudden arrest of the quantum spreading of atoms through single-atom–resolved snapshots, indicating an unconventional localized phase of matter. Such a phase defies a traditional description through statistical physics, posing new challenges to physicists. See page 1547.
Image: C. Bickel/Science