2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/135526We present our experimental investigations on the subject of nonlinearity-modified Bloch-oscillations and of nonlinear Landau-Zener tunneling between two energy bands in a rubidium Bose Einstein condensate in an accelerated periodic potential. Nonlinearity introduces an asymmetry in Landau-Zener tunneling. We also present measurements of resonantly enhanced tunneling between the Wannier-Stark energy levels for Bose-Einstein condensates loaded into an optical lattice.Chapter of "Nonlinearities of Periodic Structures and Metamaterials" (edited by C. Denz, S. Flach, and Yu. Kivshar) to be published by SpringerOther Condensed Mattertext