All-NbN edge junction nanobridges have been reproducibly fabricated. They had nearly ideal characteristics: sharply defined critical current, high resistance100Ω, sharp gap structure at about 4 mV, large IoRn products, and low excess current. The sharp LC resonance step at about 1.5 mV was observed in the nanobridge SQUID's. The noise equivalent power was NEP10-19 W/Hz in Josephson mixing at 101 GHz.

The designs and experiments for the carousel SQUID logic gate are pursued. The novel rf-magnetoron cathode is employed for the formation of tunnel barriers to obtain stable Josephson junctions for heat-cycles with small leak current. The sharp changes of a gate current by the applied control current are observed in the fabricated carousel SQUID gate.

The magnitude of low frequency noise is studied in a Nb-(nanoconstrictions)-NbN system with adjustable current-voltage characteristics. We find that the magnitude of low frequency noise decreases sharply with increasing the subgap conductivity of the device. We suggest a qualitative explanation of this observation in terms of gradual build up of the nanoconstriction region by field assisted growth. The decrease of low frequency noise is related to the "cleanliness" of the system as measured by the amount of Andreev reflection-related conductivity. The scaling of the magnitude of low frequency noise with device resistance is also discussed.

Thermal oxidation and liftoff technique have been used to fabricate the niobium nm bridge on an edge junction. The bridges had an effective length of less than 50 nm and width of 2 µm. Experimental results of the threshold curves of the DC-SQUID at 4.2 K are in excellent agreement with calculations based on a sinusoidal current-phase relation. Very sharp microwave-induced steps were also observed, and the bridges were found to show Josephson effect in a wide range of temperature.