This is an invention of a superconductive device that is equipped with a first superconductive electrode, a second superconductive electrode and a junction that is made of a superconductive material that connects these superconductive electrodes, wherein there are 2-terminal or 3-terminal superconductive devices that use a junction that is in a superconductive state that is weaker than the first and the second superconductive electrodes or in a normal conductive state that is near the superconductive state. The differences between the critical current, the critical temperature, the pair potential and the carrier densities of the first and the second superconductive electrodes and the junction are used as a means of putting the junction in the states mentioned above. Based on the methods mentioned above, a superconductive device which has few pattern rule restrictions and which is easy to fabricate can be offered. And in the case of the 3-terminal superconductive device, the switching characteristics can be improved.
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