  In this paper we have considered the interaction of a Jaynes and Cummings
system with the electromagnetic field in its vacuum state and, solving the
dynamical problem, we have analyzed the amount of entanglement induced in the
bipartite system (atom + cavity mode) by the common electromagnetic reservoir.
This has allowed us to quantitatively characterize the regime under which
field-induced cooperative effects are not vanished by dissipation. Once the
Decoherence Free Regime is reached, transient entanglement tends to become
stationary and, therefore, usable for quantum gate implementation.
