Abstract: The present invention provides a superconducting device including a substrate, a first superconducting pattern formed on the substrate, an insulating pattern formed on the first superconducting pattern, and a second superconducting pattern formed at the uppermost level in the multilayered superconducting pattern. A barrier layer of a Josephson junction is formed on the lower side of, or within the second superconducting pattern. The second superconducting pattern constitutes a circuit element on the insulating pattern.

Abstract: According to the present invention, there is provided a superconducting circuit including a Josephson tunnel junction 1 and a load resistor 2 connected in parallel to the Josephson tunnel junction, in which a current source 5 is connected to the input terminal for the Josephson tunnel junction 1 and which has a pulse generator 3 in order to superimpose a pulse current to the current i from the current source 5.As the input signal, a current pulse is given to the current i within the range of below the critical current of the Josephson tunnel junction by means of the foregoing pulse generator 3 so that an excellent separation of the input and output is achieved without using any magnetic coupling circuit.

Abstract: A superconducting circuit system comprises a biasing circuit for producing a bias current that changes periodically, and a superconducting rectifier circuit driven by the bias current. The superconducting rectifier circuit is supplied with a first pulse train including therein positive and negative pulses in synchronization with the bias current and produces a second pulse train of unipolar pulses in response to a transition of a Josephson junction caused by the pulses of the first pulse train.

Abstract: This is a superconducting analog-to-digital converter for producing a digital output signal which is a function of an analog input signal. The analog-to-digital converter uses a nonhysteresis-shunted Josephson junction, an input superconducting inductor, and an output Josephson junction, connected in superconducting loop relationship. A flux proportional to an analog input signal is coupled into the input inductor and a constant bias current source connected such that the current divides between the nonhysteresis-shunted Josephson junction and the output Josephson junction with the bias current source providing a current of at least about the sum of the critical currents of said Josephson junctions to provide voltage pulses across the nonhysteresis-shunted Josephson junction even with a constant level of flux. A Josephson junction integrating counter circuit is connected to sense the ac portion of voltage across the output Josephson junction and the Josephson junction integrating counter circuit is gated.

Abstract: In a time domain reflectometer a first step generator may include two branches of elements which are current sensitive and will produce a gap voltage if the current exceeds a specific threshold. Each branch may include either Josephson junction devices or tunnel diodes. When a trigger signal plus a bias current exceed a threshold value a first one of the elements in a first branch produces a gap voltage and diverts current to the second branch. The current causes all of the elements in the second branch to produce gap voltages and the current is diverted back to the first branch to switch the states of the remaining elements of the first branch. Once all of the elements in both branches produce gap voltages, the total signal produced by these elements is transmitted to a third output branch. The circuit produces a fast step signal and lends itself to expansibility whereby the amplitude of the step signal can be varied by varying the number of elements in the branches of the circuit.

Abstract: A superconducting circuit comprises a quantum flux parametron. In the superconducting circuit, at least one of two Josephson devices is a voltage controlled superconducting device, the critical current of which can be controlled by applying a voltage. By adjusting the applied voltage, the critical currents of the two Josephson devices can be equalized. If an input signal is used as the applied voltage, the input signal can be isolated from an output signal. And further, if both critical currents of the two Josephson devices are increased after an input signal is supplied, the input signal can be stably amplified.