COLD BOSONIC ATOMS IN OPTICAL LATTICES

The dynamics of an ultracold dilute gas of bosonic atoms in an optical lattice can be described by a Bose-Hubbard model where the system par ameters are controlled by laser light. We study the continuous (zero t emperature) quantum phase transition from the superfluid to the Mott i nsulator phase induced by varying the depth of the optical potential, where the Mott insulator phase corresponds to a commensurate filling o f the lattice (''optical crystal''). Examples for formation of Mott st ructures in optical lattices with a superimposed harmonic trap and in optical superlattices are presented. [S0031-9007(98)07267-6].