The superconducting state is a superfluid state of the Cooper pairs. The energy gap is nothing else but the energy needed to break up Cooper pairs. This will of course destroy th esuperconducting state. The phase of this wavefunction will become very important in the dicussion of the Josephson effect. Single electrons can tunnel through only, because cooper pairs do not exist on the normal side.
E g is the gap energy needed to break a pair.
Return to top 12.d. Josephson junctions Brian Josephson proposed to form junctions from two superconductors. His idea was that Cooper pairs will also be tunnel through narrow junctions, not only single electrons. At zero phase difference and no applied field there is no reason for tunneling. Quantum mechanically the rate can only be a function of the phase difference.