Orbital angular momentum transfer via spontaneously generated coherence

Abstract

We study the orbital angular momentum (OAM) transfer from a weak Laguerre–Gaussian (LG) field to a weak plane wave in two closed-loop three-level V-type atomic systems. In the first scheme, the atomic system has two non-degenerate upper levels where the corresponding transition is excited by a microwave plane wave. It is analytically shown that the microwave field induces an OAM transfer from an LG field to a generated third field. It is demonstrated that the efficiency of the OAM transfer decreases when the thermal velocity distribution of atoms is considered. In the second scheme, we consider a three-level V-type atomic system with two near-degenerate excited states and study the effect of the quantum interference due to the spontaneous emission on the OAM transfer. It is found that spontaneously generated coherence (SGC) induces the OAM transfer from the LG field to the weak planar field, and the OAM transfer does not occur in the absence of the SGC. The suggested models offer a rather simple method for the OAM transfer that can be used in quantum information processing and data storage.