Low-disorder quantum wire with gate-tunable width and electron density

We have fabricated quasi-one dimensional (1D) quantum wires based upon a novel GaAs/AlGaAs heterostructure in which carriers are induced by an epitaxially-grown n/sup +/-GaAs gate rather than by modulation doping, thus minimising disorder. By using side-gates to further constrain the electrons at the centre of the wires, we observe at low temperatures a quantisation of the resistance, indicative of ballistic transport through the constriction. Motivated by theoretical predictions concerning electron correlation effects in 1D, we report initial studies of the dependence of the observed conductance plateaux upon temperature and electron density.