Coherent and Incoherent Optical Processes and Phase Sensitive Adiabatic States

Abstract

The interaction of a quantum system (QS) with an electromagnetic field (EMF) represents a basical phenomenon for wide range of physical processes. In the optical phenomena, the main attention is normally paid to the evolution of the parameters of the optical fields. Among these, the optical phase plays a basical role when the optical processes are coherent. Since the field and matter (that mediates the interaction between the optical fields) participate in an apparently equivalent way in the interaction, it is naturally to rise up the question “What happens with the material phase?”. It seems that the answer of this question is predetermined by the orthodoxal quantum mechanics, which gives physical meaning only to the modulus of the state vector. Thus, despite that the Schrödinger’s equation actually determines the evolution of the entire state vector, the physical state of the QS remains determinate up to an arbitrary, constant (in configurational space) phase factor with unit modulus. This phase factor is irrelevant to the physical processes, that is - unobservable [1,2].