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.

A Josephson computer device called a carousel SQUID is proposed which uses an interferometer capable to be used as both a memory cell and logic gate. The principle of the operation of carousel SQUIDs is the rotation of a fluxoid quantum in the device, which makes the device to have excellent performances as computer ones. The memory cell stores one fluxoid quantum and is non-destructive read-out one. For the logic gate, the current gain is much larger than unity and input signal is isolated from the logic gate.

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.