Absorption And Dispersion Characteristics Of Rydberg Atoms In A Two-field-driven System

Rydberg atom with large main quantum number exhibits the characteristics that other neutral atoms don't possess since outer electron is excited to a highly excited state,such as long life,Large radius,strong electric dipole moment,etc.,whose characteristics have very broad application prospects in quantum communication.Based on the semi-classical theory of the interaction of light and matter,this paper studies the influence of parameters on the detection absorption and dispersion by using the stepped three-level Rydberg atomic system under the action of two light fields,and the following main results have been achieved:It's found by analytical simulations that the detection absorption and dispersion exhibit the characteristics of a two-level system when the detection field is fixed and the coupling field is increasing.In the process of increasing the coupling field intensity,the strong absorption peak appears at the resonance frequency of the detection field,whose value reaches the maximum and then gradually decreases,and the absorption spectrum evolves into a double-peak structure symmetrical about the detection resonance frequency.There is no EIT phenomenon in the whole process.Before the detection absorption peak reaches the maximum value,abnormal dispersion appears near the resonant frequency,while normal dispersion appears far away from the resonant frequency.After the detection absorption spectrum evolves into a double-peak structure,the abnormal dispersion at the resonance frequency changes to normal dispersion,however,the now dispersion effect is poor.Changing the longitudinal relaxation rate between the energy levels,it is found that the relaxation between the energy levels |2> and |3> will inhibit the detection absorption when it is small,while the small relaxation between |1> and |2> will promote the absorption at the detection resonance,and the quantum coherence phenomenon similar to EIT is shown when the relaxation rate is reduced to a certain extent.When relaxation rate between |1> and |2> increases to 1.5GHz,the detection absorption will have symmetrical and equal negative absorption double peaks,that is,the phenomenon of optical amplification is shown.It is found that the law that the influence of various parameters on the detection absorption and dispersion followed has not changed when the detection field is strong compared with the coupling field.The difference is that the detection absorption,dispersion and other characteristic values increase accordingly,and the detection absorption spectrum has obvious power broadening,whose specific performance is that the line width and the detection field Rabi frequency satisfy the quadratic relationship when the detection field is smaller than the optical transition linewidth,while there is a linear relationship between line width and the frequency when the detection field is greater.