The Study On Quantum Coherent Imaging Of N-Type Four Level System

The electromagnetically induced transparency(EIT)effect induced by quantum interference one of the special fields in quantum optics.Under the condition of EIT,the atomic medium exhibits unique optical properties,such as high transmission,steep dispersion and enhanced nonlinearity.In this paper,based on the N-type level87 Rb model,using the density matrix method describes the absorption and dispersion properties of the signal light.A special gradient-index electromagnetically induced transparency medium is induced with a Gaussian control field,which can be realized in a four-level87 Rb cold atomic cloud.Special directional self-imaging and imaging transforming properties are studied with different waist radius.The study has been presented to show influences of the temperature on the imaging properties,for example,the imaging position,the corresponding imaging quality,and the imaging contrast ratio in four-level Doppler broadening medium with electromagnetically induced transparency(EIT).Some novel results are achieved,which have potential application in image transformation or image processing.This paper including several chapters: we mainly describe the discovery of electromagnetically induced transparency and quantum interference effects in the first chapter.We present the model and equations of N-type level in the second chapter.In the next two chapters,we discuss the special directional self-imaging in cold atomic system.By the method of plotfittng GRIN medium,the positions of special directional imaging are presented.With numerical simulation,we simulate the positions of special directional imaging.We also present influences of the temperature on the position of the self-imaging and the corresponding imaging contrast ratio in four-level Doppler broadening medium.At last,we summarize the full paper.