Simple electronic analog of a Josephson junction

Abstract

We describe an electronic analog of a resistively shunted Josephson junction in which the quantum phase difference of a real junction is represented by the phase difference between two oscillators, each running at approximately 100 kHz. Only three integrated circuits and an external reference oscillator are required. The circuit operates on a time scale approximately 109 times slower than a typical real junction and allows easy visualization of the time-dependent quantum phenomena of the ac Josephson effect. Characteristic current–voltage curves and waveforms obtained with the analog are shown for the cases of dc and dc plus ac current bias, and for the sudden reduction of the critical current in a current-fed, resistively loaded junction, which models a magnetically switched Josephson computer element. Other applications of the analog are discussed. © 1981 American Association of Physics Teachers