(a) Force applied to the optical lattice against time through frequency modulation of a lattice laser beam in Struck et al. . By appropriately choosing times T1 and T2 the induced Peierls phase is adjusted. (b) The effective magnetic field indicated by the red arrow subtends the solid angle θ, shown as light red shading, when an atom hops from site to site in the setup of Jiménez-García et al. . The phase θ is imprinted on the atomic wave function in this process. (c) Measured quasimomenta when adiabatically changing θ as a function of time. The symbol kFBZ indicates the edge of the first Brillouin zone.