On nonuniversal conductance quantization in high-quality quantum wires

We present a theoretical analysis of recent experimental results of Yacoby et al. on transport properties of high quality quantum wires. We suggest an explanation of observed deviations of the conductance from the universal value $2e^2/h$ per channel in the wire. We argue that at low temperatures and biases the deviation can be a consequence of anomalously enhanced backscattering of electrons entering the 2DEG from the wire and is not connected to intrinsic properties of 1DEG. On the other hand, the fact that at higher biases plateaus at values of the differential conductance exceeding $2e^2/h$ are observed can possibly be a manifestation of electron-electron interactions in 1DEG.