Theory of generalized Josephson effects

Understand

The DC Josephson effect is the flow of supercurrent across a weak link between two superconductors with a different value of their order parameter, the phase.

• We generalize this notion to any kind of spontaneous continuous symmetry breaking.
• The quantity that flows between the two systems is identified as the Noether current associated with the broken symmetry.
• The AC Josephson effect is identified as the oscillations due to the energy difference between the two systems caused by an imposed asymmetric chemical potential.