  In this paper, we study the exact entanglement dynamics of two two-level
atoms in a dissipative cavity. We use the Gardiner-Collett Hamiltonian to model
the dissipative cavity, in which, we assume that the two atoms resonantly
interact with the cavity field and the cavity field itself interacts with the
surrounding medium. Then, with the help of the Fano's technique, we show that,
this system can be regarded as two atoms interacting with a heat bath. In such
a case, we find that, there exists a decoherence-free state that does not
evolve in time. At this time, there exists a so-called super-radiant state
which decays in time due to dissipation. At last, we use the quantum Zeno
effect to preserve the entanglement which already has been stored in the
system.
