investigation of spin squeezing and entanglement for atom-field entangled state

In this article, spin squeezing is studied for entangled atom-field state generated by jaynes-cummings modelwith large detuning. we prove that the created entangled state is a spin-squeezed state and regard the behaviorof spin squeezing parameter as a function of the coherent field amplitude. moreover, we will show that spinsqueezing implies pairwise entanglement for two-qubit states. to this aim we will use concurrence asentanglement measure and demonstrate the relation between the squeezing parameter and concurrence forentangled atom-field state.