Landau-Zener Bloch oscillations with perturbed flat bands (1602.08691v1)

Abstract: Sinusoidal Bloch oscillations appear in band structures exposed to external fields. Landau-Zener (LZ) tunneling between different bands is usually a counteracting effect limiting Bloch oscillations. Here we consider a flat band network with two dispersive and one flat bands, e.g. for ultracold atoms and optical waveguide networks. Using external synthetic gauge and gravitational fields we obtain a perturbed yet gapless band structure with almost flat parts. The resulting Bloch oscillations consist of two parts - a fast scan through the nonflat part of the dispersion structure, and an almost complete halt for substantial time when the atomic wave packet is trapped in the original flat band part of the unperturbed spectrum, made possible due to LZ tunneling.