Transport through a 2DEG channel with superconducting boundaries

We have investigated transport through a channel with superconducting boundaries where electrons are confined by Andreev reflection. Superconducting phase-sensitive transport is discussed using qualitative arguments. The transfer resistance R_t through the channel as well as the resistance R_i between the injector and the channel have been measured as a function of the phase difference ø between the superconducting boundaries. It is not yet clear that the observed oscillation in resistance can be attributed to quasiparticle phase-sensitive transport. The oscillation amplitude in R_t due to the transmitted current modulation is less than 0.1% in this experiment.