9414160 Xiao The program will investigate electronic transport in mesoscopic structures composed of a normal metal (N) and a supercpnductor (S), two states with sharply contrasted electronic states. The objective is to develop scientific understanding of the new phase- coherent electronic transport expected to occur in such N-S structures, and to test, for the first time, recently developed theories which explain quantum transport in such structures. The PI will carry innovative design, fabrication, and transport measurements of three N-S structures: microjunctions, composite wires, and multiply connected structures. Important issues such as interplay between the two types of phase coherence in N and S, and its effects on the quantum transport will be invested. The research will either lead to novel quantum transport mechanism or will modify that in mono-component structures. % % % Mesoscopic structures are obtained when the size of metallic samples is reduced to submicron range. In such systems, the particle wave duality of the electrons plays an important role in the transport of electrical current, and a new less understood electronic mechanism emerges. This research will investigate the electronic transport in mesoscopic structures composed of a normal metal and a superconductor, which are two states with sharply contrasted electronic structures. The PI will investigate the new quantum electronic transport and provide test for new theories. The research includes innovative design and fabrication of microstructures, composites wire, and multiply connected normal- superconductor structures, and transport measurements. Research in this area will benefit the continuing process of device miniaturization and integration. ***