Steady-state entanglement of two atoms

We discuss the problem of creation of a steady-state entanglement in a system of two two-level atoms which are separated by an arbitrary distance T-12 and interact with each other via the dipole-dipole interaction and both are driven by a laser field. Two measures of entanglement, concurrence and negativity, are used to quantify the amount of entanglement in the system. They are compared with the populations of the maximally entangled collective states of the two-atom system. It is shown that considerable amount of entanglement can be created in case of non-identical atoms driven by a strong laser field.