Quantum electrodynamics formulation of the Josephson tunnelling theory

The local ground state polarisation (complex) Schwinger Lagrangian is given corresponding to the Josephson theory of tunnelling in a junction capacitor. In the quantum electrodynamic theory there are two regimes of interest: (i) for voltages small on the scale of the gap eV<2δ, the motion is that of a 'quantum pendulum' with no dissipative damping; (ii) for voltages large on the scale of the gap eV>2δ, a finite shunt conductance is 'turned on' describing the dielectric breakdown of the junction capacitor. (author)