ENHANCED LASER COOLING AND STATE PREPARATION IN AN OPTICAL LATTICE WITH A MAGNETIC-FIELD

We demonstrate that weak magnetic fields can significantly enhance las er cooling and state preparation of Cs atoms in a one-dimensional opti cal lattice. A field parallel to the lattice axis increases the vibrat ional groundstate population of the stretched state \m=F] to 28%. A tr ansverse field reduces the kinetic temperature. Quantum Monte Carlo si mulations agree with tile experiment, and predict 45% ground-state pop ulation for optimal parallel and transverse fields. Our results show t hat coherent mixing and local energy relaxation play important roles i n laser cooling of large-F atoms.