  We analyze the multipartite entanglement evolution of three-qubit mixed
states composed of a GHZ state and a W state. For a composite system consisting
of three cavities interacting with independent reservoirs, it is shown that the
entanglement evolution is restricted by a set of monogamy relations.
Furthermore, as quantified by the negativity, the entanglement dynamical
property of the mixed entangled state of cavity photons is investigated. It is
found that the three cavity photons can exhibit the phenomenon of entanglement
sudden death (ESD). However, compared with the evolution of a generalized
three-qubit GHZ state which has the equal initial entanglement, the ESD time of
mixed states is later than that of the pure state. Finally, we discuss the
entanglement distribution in the multipartite system, and point out the
intrinsic relation between the ESD of cavity photons and the entanglement
sudden birth of reservoirs.
