We derive a master equation describing the collective decay of two-level atoms inside a single mode cavity in the dispersive limit. By considering atomic decay in the collective thermostat, we found a decoherence-free subspace of the multiparticle entangled states of the $W$-like class. We present a scheme for writing and storing these states in collective thermostat.

• Received 7 June 2006

DOI:https://doi.org/10.1103/PhysRevA.74.042313