Chaos-induced orbit delocalization and complex Bloch oscillations in semiconductor superlattices

We show how semiconductor superlattices can be used to provide a new type o f quantum chaotic system that is accessible to experiment. When a magnetic field is tilted relative to the superlattice axis, the semiclassical orbits of electrons confined to a single miniband undergo a controllable transiti on from stable Bloch oscillations to chaotic orbits. The onset of chaos del ocalizes the electron paths and generates complex trajectories that extend across many periods of the superlattice. We show that the chaotic motion ha s a fundamentally different origin to that reported for previous semiconduc tor structures. (C) 1999 Elsevier Science B.V. All rights reserved.