Resonant multiple Andreev reflections in mesoscopic superconducting junctions

We investigate the properties of subharmonic gap structure (SCS) in superco nducting quantum contacts with normal-electron resonances. We find two dist inct features of the SGS in resonant junctions which distinguish them from nonresonant point contacts: (i) The odd-order structures on the current-vol tage characteristics of resonant junctions are strongly enhanced and have p ronounced peaks, while the even-order structures are suppressed, in the cas e of a normal electron resonance being close to the Fermi level. (ii) Huge current peaks develop at eV = +/- 2E(0) where E-0 indicates the distance of the resonance to the Fermi level. These properties are determined by the e ffect of narrowing of the resonance during multiple Andreev reflections and by overlap of electron and hole resonances. [S0163-1829(99)14725-8].