| Definition: | macroscopic quantum effect in which, when a direct current (DC) voltage U is applied across a Josephson junction, an alternating current of Cooper pairs flows by tunnel effect through the junction, generating the emission of electromagnetic wave having a frequency f proportional to the applied voltage and satisfying the relation: f = 2eU/h where h is the Planck constant and e is the elementary electric charge Note 1 to entry: The AC Josephson effect also manifests itself conversely so that, when a Josephson junction is irradiated by an electromagnetic radiation of frequency f, the voltage across it can assume quantized values equal to (h/2e)nf, where n is an integer. Note 2 to entry: f/U = 483,6 MHz/μV.
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