Emergence of phase correlation in Ramsey setting from superoperator point of view

A comparative analysis of four different approaches to the notion of phase in quantum optics is carried out in the framework of the Ramsey interferometer scheme, where phase correlation between two spatially separated quantum electromagnetic modes emerges as a consequence of resonant two-level atoms traversing the modes. The measure of correlation is expressed through the dispersion of the inter-mode phase difference cosine. A simple law obtained within a semiclassical approach is used to verify the quantum phase approaches. Somewhat unexpectedly, the definite advantage of the superoperator method by M.Ban is revealed.