We examine dark quantum superposition states of weakly bound Rb2 Feshbach
molecules and tightly bound triplet Rb2 molecules in the rovibrational ground
state, created by subjecting a pure sample of Feshbach molecules in an optical
lattice to a bichromatic Raman laser field. We analyze both experimentally and
theoretically the creation and dynamics of these dark states. Coherent
wavepacket oscillations of deeply bound molecules in lattice sites, as observed
in one of our previous experiments, are suppressed due to laser-induced phase
locking of molecular levels. This can be understood as the appearance of a
novel multilevel dark state. In addition, the experimental methods developed
help to determine important properties of our coupled atom / laser system.Comment: 20 pages, 9 figure