Study On Coherence Effect In Anti-relaxation Coated Vapor Cells

Atomic coherent effects produced in the interaction of coherent light and atoms,which has been intensively studied.There are spontaneous radiation,spin exchange collisions,atom collisions with walls,and other atomic depolarization caused by atomic thermal motion and collisions in atomic coherence processes.Vapor cells with anti-relaxation coated walls or inerted buffer gas allow atoms to preserve their ground-state coherence during wall collisions.In this article we have a further investigate on electromagnetically induced transparency(EIT)and coherent population trapping(CPT)in anti-coated 87Rb vapor cells theoretically based on Kazakov's research.First,we solve the Bloch equations in a three-level model.Simulate the atoms intervals in the "bright" and "dark" regions of the laser beam alternately in the coated cell as a Ramsey pulse sequence,obtain the steady-state average expression in three-level of the model by take the appropriate average on all possible paths.Then we use Matlab to program the obtained results in a nested way,and fit the model to CPT and EIT respectively.The parameters of 87Rb atom working in the laboratory were brought in,the CPT and EIT line patterns were simulated.The results show that the linear double structure is formed by atoms passing through the laser region repeatedly.The change of CPT particle population with the probability of elastic collision was also fitted,and the coherence of quantum states was analyzed.Finally,by fitting the change of EIT with the spot area and power,it shows the formation mechanism of EIT wide peak line width and narrow peak line width.