COOPERATIVITY AND ENTANGLEMENT OF ATOM-FIELD STATES

The Jaynes-Cummings model of a single two-level atom interacting with a quantized single-mode coherent field generates at the half-revival t ime a dynamically disentangled atom-field state. At such times, the fi eld is in asymptotically pure Schrodinger cat state, a macroscopic sup erposition of distinct field eigenmodes. In this paper we address the problem of field purity when a second atom is allowed to interact with the cavity mode and becomes entangled with the first atom via their m utual cavity field with which they interact. We employ the collective Dicke states to describe the cooperative effects on the entanglement a nd show that the second atom spoils the purity of the field state exce pt for special cases of the atom-field coupling or of initial conditio ns.