Constructing atom optical elements from periodic potentials of finite length

The manipulation of the dispersion properties of a Bose-Einstein condensate (BEC) with moving optical lattices has enabled considerable control of atomic matter waves and, more recently, the generation of bright matter wave solitons [1]. Here, we computationally propagate BEC's through periodic optical potentials of finite spatial/temporal lengths. It is seen that to vary the effective mass requires potentials that are relatively strong compared to the transverse waveguide confinement. The role of both the linear and non-linear wave mechanics in practical issues such as loading the atoms into the potentials are explored. We also report on work in progress examining matter waves propagation through a chip-based magnetic lattice [2]. \\ $[1]$ Eiermann, B \textit{et.al} Phys.~Rev.~Lett. \textbf{92} 230401 (2004) \\ $[2]$ G{\"u}nther, A \textit{et.al} Phys.~Rev.~Lett. \textbf{95} 170405 (2005)