1. Magnetotransport through a one-dimensional superlatticeThe device studied by Kouwenhoven et al.250 is shown in the inset of Fig. 107. A narrow channel is defined in the 2DEG of a GaAs-AlGaAs heterostructure by two opposite gates. One of the gates is corrugated with period a = 200 nm, to introduce a periodic modulation of the confining potential. At large negative gate voltages the channel consists of 15 cavities [as in Section IV.D.2(b)] coupled in series. The conductance of the channel was measured at 10mK in a fixed magnetic field of 2T, as a function of the voltage on the gate that defines the smooth channel boundary. The results, reproduced in Fig. 107, show two pronounced conductance dips (of magnitude 0.1 e2/h), with 15 oscillations in between of considerably smaller amplitude. The two deep and widely spaced dips are attributed to minigaps, the more rapid oscillations to discrete states in the miniband.This interpretation is supported in Ref.250 by a calculation of the transmission probability amplitude tn through n cavities in series, given by the recursion formula