Supercurrents through gated superconductor-normal-metal-superconductor contacts: The Josephson transistor - art. no. 054520

We analyze the transport through a narrow ballistic superconductor-normal-m etal-superconductor Josephson contact with nonideal transmission at the sup erconductor-normal-metal interfaces, e.g., due to insulating layers, effect ive mass steps, or band misfits (SIN interfaces). The electronic spectrum i n the normal wire is determined through the combination of Andreev reflecti on and normal reflection at the SIN interfaces. Strong normal scattering at the SIN interfaces introduces electron- and holelike resonances in the nor mal region that show up in the quasiparticle spectrum. These resonances hav e strong implications for the critical supercurrent I-c that we find to be determined by the lowest quasiparticle level: tuning the potential mu (xo) to the points where electron- and holelike resonances cross, we find sharp peaks in I-c, resulting in a transistor effect. We compare the performance of this resonant Josephson-transistor with that of a superconducting single electron transistor.