  A method for generating entangled cat states of two modes of a microwave
cavity field is proposed. Entanglement results from the interaction of the
field with a beam of atoms crossing the microwave resonator, giving rise to
non-unitary dynamics of which the target entangled state is a fixed point. We
analyse the robustness of the generated two-mode photonic "cat state" against
dephasing and losses by means of numerical simulation. This proposal is an
instance of quantum reservoir engineering of photonic systems.
