An electronic fast-switching device consisting of layers of superconducting metal separated by a thin layer of insulator through which low current flows but increased current causes the insulator to block the flow.

约瑟夫森接合。以薄绝缘膜隔开两个超导体，无电位差时有低电流流过绝缘膜，而施以电压时绝缘膜即使电流中断。