FLUX AND VOLTAGE PERIODIC BEHAVIOR IN A SUPERCONDUCTING WEAK-LINK RING

Starting with a simple Lagrangian for the electromagnetic field with b roken gauge symmetry, we derive an effective circuit Hamiltonian for a superconducting weak-link ring. The energy eigenstates of this Hamilt onian exhibit sensitivity to both external magnetic flux and an applie d Faraday law voltage. We show that the flux periodicity of the rf SQU ID ring, and the voltage periodic behaviour found in ultra-small-capac itance weak-link rings, can be seen as limiting cases of a more genera l phenomenon.