Ramsey interferometers as a test of open system evolution or a modified quantum-mechanical model

. By applying the basic concept of the density matrix in an open quantum system and modification of quantum mechanics, we derive the Kossakowski-Lindblad equation, and different properties of this equation are reviewed. Next, a pedagogical approach is used to present Ramsey's trick for the linear modification of quantum mechanics. We discuss how an open quantum mechanics or its modification changes the fraction of excited states in Ramsey Interferometers.