I am doing some reading about superconductors and Josephson Junctions and was wondering about one of their exhibited behaviors. I read a statment claiming that if a frequency (AC current) is applied to the terminals of a Josephson Junction by microwave irradiation then the current of cooper pairs tends to syncronize with that frequency causing a direct voltage to appear at the terminals. My questions are: 1.) Is there a specific way in which the microwave irradiation must be introduced into the system so that this behavior occurs? 2.) Does the amount of irradiation affect the direct voltage that appears or is it a set level depending on something like material characteristics?