We report possibility of generating entanglement and steady entanglement between two identical atoms in free space with a very natural way when their spatial separation is on the order of wavelength or less. We show a dynamical creation of entanglement and steady entanglement due to the radiative coupling with different separable initial atomic states and study the entanglement properties about this atomic subsystem. Not only the creation of steady state entanglement is decided by the initial atomic states, but also the magnitude of the entanglement and the steady state entanglement are found to be strongly dependent on the initial states. We derive a master equation for the atomic subspace and solve it analytically to show how the spontaneous emission from the two atoms system induces entanglement and steady entanglement, the crossing coupling terms in master equation can enhance the entanglement value.

We report the transfer fidelities of two-qubit pure state via a two-qubit Heisenberg XY Z spin model under a nonuniform magnetic field. It shown us that not only the average fidelity can be enhanced evidently but also the ideal fidelity region can be broadened by introducing the interaction of z component of two neighboring spins J z . Decreasing the anisotropy parameter γ also can improve F a and result in ideal fidelity. Our study on the average fidelity of this quantum channel system also shows that for any finite value of temperature T we can obtain the ideal average fidelity by improving the inhomogeneous magnetic field b. F a is infinitely close to the maximum value of classical communication 2/3 with increasing b. While increasing the uniform field B can not do this, F a are always inferior to 2/3 for enough larger B.