Experimental and theoretical work will be carried out on quantum and charging energy effects in sub-micron sized tunnel junctions, on high-temperature superconductivity, and on arrays of Josephson junctions; ongoing work on quantum conductance fluctuations in amorphous microbridges will be completed this year. The proposed work will be carried out with the aid of our new clean room microfabrication facility and microwave facility, together with our dilution refrigerator facility, which allows us to reach the low temperatures which are required for the work on quantum effects in small junctions. The objective of the work on small tunnel junctions is to understand the interplay between forces dependent on the phase of the superconducting pair wavefunction and those dependent on deviations from electrical chage neutrality; devices sensitive to the charge of a single electron may be possible. Their work on high temperature superconductors is focussed on the phenomena of flux creep and flow with associated energy dissipation; their emphasis is on ac measurements at frequencies from dc up to microwaves. The potential practical significance of these materials is well- known. Their work on fabricated Josephson junction arrays will emphasize their use as model systems serving as a controlled laboratory prototype for study of the behavior of granular high temperature superconductors.
