FIG.42 (a) Narrow channel connectin

FIG.42 (a) Narrow channel connecting two wide electron gas regions, having a chemical potential difference δμ. (b) Schematic dispersion relation in the narrow channel. Leftmoving states (k > 0) are filled up to chemical potential EF, right-moving states up to EF + δμ (solid dots). Higher-lying states are unoccupied (open dots). FIG.43 Generalization of the geometry of FIG.42a to a multireservoir conductor. FIG.44 Point contact conductance as a function of gate voltage at 0.6 K, demonstrating the conductance quantization in units of 2e2/h. The data are obtained from the two-terminal resistance after subtraction of a background resistance. The constriction width increases with increasing voltage on the gate (see inset). Taken from B. J. van Wees et al., Phys. Rev. Lett. 60, 848 (1988).