Influence of dissipation on the entanglement of N two-level atoms located in one cavity or N cavities

We investigate the influence of dissipation on the entanglement among N identical two-level atoms. We analyse the situation of N two-level atoms in a dispersive cavity or in N dispersive cavities, both in W-like and in GHZ states for N atoms. By considering the Jaynes-Cummings model in the dispersive regime, and a master equation formalism, we compute the time evolution of the entanglement of the atoms, in a variety of situations. We find that, depending on whether the atoms are located in one or N cavities, and on their initial entangled state, the subsequent dynamics will be very different, specifically, exponential decay to coherent oscillations, exponential decay to steady values, or collapse and revival.