Researchers from Ludwig Maximilians Universität in Munich, Germany, Max Planck Institut für Quantenoptik in Garching, Germany, and the Swiss Federal Institute of Technology in Zurich have created a new state of matter by exposing a Bose-Einstein condensate to a 3-D optical lattice potential. In their report of the work, which appeared in the Jan. 3 issue of Nature, they suggest that the technique may find applications in atom interferometry and quantum computing.The researchers used an 852-nm laser diode to generate a lattice of standing waves in a rubidium condensate. By turning off the trap and imaging the matter-wave interference pattern, they confirmed that increasing the optical potential leads to a phase change in the sample from a superfluid to a Mott insulator state, driven by quantum mechanical rath-er than thermal effects.