  We address the enhancement of electron drift in semiconductor superlattices
of nanometre scale that occurs in combined electric and tilted magnetic fields
if Bloch oscillations become resonant with cyclotron rotation in the transverse
plane. We uncover the true dynamical mechanism of the phenomenon: the electron
dynamics at relevant time-scales is regular or almost regular, contrary to the
widespread belief that the enhancement arises through chaotic diffusion between
collisions. The theory provides an accurate description of earlier numerical
simulations, predicts new remarkable features verified by simulations, and
suggests new ways of controlling resonant transport.
