Kinetic theory of a quantum particle interacting with a dissipative environment
We develop a kinetic theory for the real-time response of a quantum particle interacting with a macroscopic reservoir. We calculate in the low-damping limit the width and bath-induced frequency shift of the metastable tunneling levels of a resistively shunted Josephson junction and the enhancement of the tunneling rate upon the application of a weak microwave field. The results agree with experiment without adjustable parameters. At low temperatures the equation of motion for the phase of the junction can be written as that of a spin-(1/2) object in a time-dependent magnetic field. © 1987 The American Physical Society.