  We study the dynamics of genuine multipartite entanglement for a system of
four qubits. Using a computable entanglement monotone for multipartite systems,
we investigate the as yet unexplored aspects of a cavity-reservoir system of
qubits. For one specific initial state, we observe a sudden transition in the
dynamics of genuine entanglement for the four qubits. This sudden change occurs
only during a time window where neither cavity-cavity qubits nor
reservoir-reservoir qubits are entangled. We show that this sudden change in
dynamics of this specific state is extremely sensitive to white noise.
