Generation of macroscopic superpositions in a micromaser
John J. Slosser, Pierre Meystre, Ewan M. Wright · Optics Letters · 1990
At low temperatures steady-state macroscopic superpositions can be generated in the field of a micromaser pumped by a stream of two-level atoms injected in a coherent superposition of their upper and lower states. The onset of these superpositions resembles a second-order phase transition, with the control parameter being the ratio of the atomic injection rate to the cavity damping rate.