Macroscopic Interference Effects in Resonant Cavities

We investigate the possibility of interference effects induced by macroscopic quantum-mechanical superpositions of almost othogonal coherent states - a Schroedinger cats state - in a resonant microcavity. Despite the fact that a single atom, used as a probe of the cat state, on the average only change the mean number of photons by one unit, we show that this single atom can change the system drastically. Interference between the initial and almost orthogonal macroscopic quantum states of the radiation field can now take place. Dissipation under current experimental conditions is taken into account and it is found that this does not necessarily change the intereference effects dramatically.