Ballistic electronic transport in quantum cables

We studied theoretically ballistic electronic transport in a proposed mesoscopic structure—quantum cable. Our results demonstrated that quantum cable is a unique structure for the study of mesoscopic transport. With the increasing Fermi energy of electrons, the ballistic conductance of quantum cable increases in a series of steps with different height. Besides the steps of one and two quantum conductance units ${\text{(2e}}^2\mathrm{/h),}$ conductance steps of three and four quantum conductance units can be also expected due to the accidental degeneracies (crossings) of the transverse subbands of quantum cable. As one of the cable structure parameters is varied, the width of conductance plateaus varies in the nonmonotonous way, which arises from the nonmonotonic variation of the separation between the adjoining transverse subbands. In the weak coupling limit, the first two conductance plateaus are both of just one quantum conductance unit ${\text{2e}}^2\mathrm{/h}$ for the quantum cable structure of two cylindrical wires with similar thicknesses.