Abstract
We transform the nonlinear interaction between a two-level atom and two-mode fields in a frequency-converter-type device into an inactivation governed by su(2) Lie algebra operators with phase and coupling depending on time. Under an integrability condition that relates them, we obtain a solution to the wave function. We investigate the effects of the functional dependence of the coupling and the initial state of the two-level atom on atomic inversion, entanglement, atomic variable, and entropy squeezing, as well as the autocorrelation function. The different changes for each of these phenomena are noted and displayed.