The nonlinear Wannier functions in square Kronig-Penney potential are investigated with the help of a set of exact nonlinear Bloch solutions. The nonlinear interaction makes the Wannier functions fall off as non-exponential law with distance and enhances the tunneling coupling between the neighbor sites.
The surface dynamics of supercooled liquid-glycerol is studied by scanning the thickness of the glycerol film with single photon detection. Measurements are performed at room temperature well above the glyeerol＇s glass transition temperature. It is shown that the surface dynamics of the glycerol film is very sensitive to the temperature. The linear relationship between the thickness of the film and the viscosity predicted by the Vogel Pulcher-Tammann Hesse （VFTH） law is also presented experimentally.
We theoretically analysed the linewidth of the probe absorption spectrum in a cold Cs atom-molecule system. The tunnelling coupling between the two excited molecular states, especially for the Cs atom molecule system, plays an important role in obtaining the sub-natural linewidth of the probe absorption spectrum. For example, when the tunnelling couple strength fulfils σ12=10γab1, the linewidth is only about 0.66 MHz. Moreover, since the linewidth of interest is dominated by the tunnelling coupling, the absorption peak becomes very narrow even in the case of large pump laser intensities.
