Noise-assisted transport in the Wannier-Stark system

We investigated how the presence of an additional lattice potential, driven by a harmonic noise process, changes the transition rate from the ground band to the first excited band in a Wannier-Stark system. Alongside numerical simulations, we present two models that capture the essential features of the dynamics. The first model uses a noise-driven Landau-Zener approximation and describes the short-time evolution of the full system very well. The second model assumes that the noise process correlation time is much larger than the internal timescale of the system, yet it allows for good estimates of the observed transition rates and gives a simple interpretation of the dynamics. One of the central results is that we obtain a way of controlling the interband transitions with the help of the second lattice. This could readily be realized in state-of-the-art experiments using either Bose-Einstein condensates or optical pulses in engineered potentials.