2D-1D Coupling in Cleaved Edge Overgrowth

We study the scattering properties of an interface between a one-dimensional (1D) wire and a two-dimensional (2D) electron gas. Experiments were conducted in the highly controlled geometry provided by molecular bean epitaxy overgrowth onto the cleaved edge of a high quality GaAs $/$AlGaAs quantum well. Such structures allow for the creation of variable length 1D-2D coupling sections. We find ballistic 1D electron transport through these interaction regions with a mean free path as long as $6\mu \mathrm{m}$. Our results explain the origin of the puzzling nonuniversal conductance quantization observed previously in such 1D wires.