Dynamical Bloch band suppression in an optical lattice
The first observation of dynamical suppression of Bloch bands due to an AC field is presented. The system consists of laser-cooled atoms in an optical lattice. The neutral sodium atoms in the lowest band of a 1D optical lattice are trapped. The position of the potential to realize both an intense AC field and a weak spectroscopic probe is modulated in order to directly observed band suppressions. In the theoretical analysis, the quasienergies and the corresponding coupling strengths between the first and higher bands are calculated in order to generate a prediction for the experimental spectral distributions. This calculation goes beyond the single-band and tight-binding approximations, and is in good agreement with the observed spectra.