We perform a quantum mechanical analysis of superconducting resonators
subject to dielectric loss arising from charged two-level systems. We present
numerical and analytical descriptions of the dynamics of energy decay from the
resonator within the Jaynes-Cummings model. Our analysis allows us to
distinguish the strong and weak coupling regimes of the model and to describe
within each regime cases where the two-level system is unsaturated or
saturated. We find that the quantum theory agrees with the classical model for
weak coupling. However, for strong coupling the quantum theory predicts lower
loss than the classical theory in the unsaturated regime. Also, in contrast to
the classical theory, the photon number at which saturation occurs in the
strong coupling quantum theory is independent of the coupling between the
resonator and the two-level system.Comment: 9 pages, 8 figure