We study the shape-resonance effect associated with the confined transverse superconducting modes of a cylindrical nanowire in the clean limit. Results of numerical investigations of the Bogoliubov–de Gennes equations show significant deviations of the energy gap parameter from the bulk value with a profound effect on the transition temperature. The most striking is that the size of the resonances is found to be by order of magnitude larger than in ultrathin metallic films with the same width.

• Received 21 July 2005

DOI:https://doi.org/10.1103/PhysRevB.73.012510