entangled state and the GME for the three-qubit entanglement never disappears during the death of the two-qubit entanglement. The theory of the multipartite entanglement is not fully developed and requires more insightful investigations into more- than two-party systems. We highlight here the different features of the multipartite entanglement and bipartite entanglement in the more- than two-qubit system, and have found that the GME is always robust at least in the qubits and single-mode cavity system.

![(Color online) GME for the three qubits A, B,C (dash-dotted line), negativity for the entanglement with respect to the bipartition $AB|C$ (solid line), and concurrence between A and B qubits (dashed line) obtained by the numerical method for $%
g/\protect\omega=0.1$ and $\Delta/\protect\omega =1$.[]{data-label="entanglement"}](compare.eps)

Conclusion
==========

In this work, we have extended the original GRWA by Irish for the one-qubit Rabi model to the three-qubit Dicke model by the unitary transformation. The zeroth-order approximation, equivalent to the adiabatic approximation, is suited for arbitrary coupling strengths for the large detuning case. The first-order approximation, also called GRWA, works well in a wide range of coupling strength even on resonance and much better than the RWA ones. In the GRWA, the effective Hamiltonian with the CRW interactions is 