Abstract
In this paper, we present a study of the entropy growth and degradation of entanglement due to intrinsic decoherence for some different initial states in the multi-quanta Jaynes-Cummings model. We analytically solve the Milburn equation for such JC model. Using an established entanglement measure based on the negativity of the eigenvalues of the partially transposed density matrix we find a very strong sensitivity of the maximally generated entanglement to the amount of decoherence, the multiplicity and the form of the and the initial state. Comparison with different measures of entanglement are made.