  A new mechanism is proposed for dissipatively preparing maximal Bell
entangled state of two atoms in an optical cavity. This scheme integrates the
spontaneous emission, the light shift of atoms in the presence of dispersive
microwave field, and the quantum Zeno dynamics induced by continuous coupling,
to obtain a unique steady state irrespective of initial state. Even for a large
cavity decay, a high-fidelity entangled state is achievable at a short
convergence time, since the occupation of cavity mode is inhibited by the Zeno
requirement. Therefore, a low single-atom cooperativity $C=g^2/(\kappa\gamma)$
is good enough for realizing a high fidelity of entanglement in a wide range of
decoherence parameters. As a straightforward extension, the feasibility for
preparation of two-atom Knill-Laflamme-Milburn state with the same mechanism is
also discussed.
