BALLISTIC TRANSPORT IN MESOSCOPIC SYSTEMS

Recent studies of the ballistic transport in the mesoscopic systems performed in our laboratory are reviewed in the present paper. In the first half of the present paper, we investigate the characteristics of ballistic transport in quantum wires of which the effective confined length (the effective width) varies along the direction parallel to the current. It is shown that the step-wise variation of the conductance as a function of the Fermi energy, corresponding to the ideal quantization of the conductance, is smeared when the effective confined length of the wire varies along the direction parallel to the current and when the temperature increases. In the second half of the present paper, we show the numerical results of wave functions of the stationary states for the geometry of the semi-infinite two-dimensional region with a narrow channel as an injector in the external magnetic field. In the presence of the magnetic field, we obtain a periodic peak structure in the modulus squared of the wave function along the boundary in the semi-infinite two-dimensional region, the period of which is nearly equal to the classical cyclotron diameter. Moreover, it is shown that small peaks exist between the periodic main peaks, which is considered to be one of the characteristic aspects of the quantum interference effects.