Damping mechanisms in the path-integral approach to special effects in superconductivity

Previous work on semiclassical approximations in SQUIDs (which involved Feynmanʹs path-integral technique) is here extended to damped Josephson systems. Quantum decay rates of unstable energy levels near the bottom of the quartic potential well are examined. Rates diagram is compared with that obtained for the undamped case. Agreement with Caldeira-Leggett results is discussed. A description of continuous flux measurements is developed. The spreading of the wave function leads to the treatment of flux and charge as canonically conjugate variables.