AC-FIELD-CONTROLLED ANDERSON LOCALIZATION IN DISORDERED SEMICONDUCTOR SUPERLATTICES

An ac field, tuned exactly to resonance with the Stark ladder in an ideal tight binding lattice under strong de bias, counteracts Wannier-Stark localization and leads to the emergence of extended Floquet states. If there is random disorder, these states localize. The localization lengths depend nonmonotonically on the ac field amplitude and become essentially zero at certain parameters. This effect is of possible relevance for characterizing the quality of superlattice samples, and for performing experiments on Anderson localization in systems with well-defined disorder.