Ballistic transport in quantum cylinders

We theoretically investigate the ballistic conductance of hollow quantum wires made of a two-dimensional electron gas occupying a cylindrical surface. The dependence of the conductance on the electron Fermi momentum differs drastically from the conventional case of a strip-like wire. We trace the evolution between these two cases in an exactly solvable model of a circular cylinder affected by a delta-like potential barrier along its element. We consider also a cylinder with two diametrically opposite delta-function barriers, the case representing somewhat realistic semiconductor structures. The general consequences of the boundary condition topology are also discussed. (C) 1998 Academic Press Limited.