研究了倒Y型四能级原子系统中相干控制电磁诱导透明.应用微扰理论给出一阶近似条件下,不同控制场原子系统对探测光场响应的解析式及电磁诱导透明窗宽度的解析式.在探测场为弱场时,分析了系统中控制光场强度、耦合光场强度及其失谐量对电磁诱导透明窗的影响.研究发现电磁诱导透明窗随控制光场强度的增强变宽,而随耦合光场强度的增强变窄,当探测光场与耦合光场偏离双光子共振时,透明窗外的吸收增加,透明窗变宽.在弱探测场、弱控制场条件下,分析了初始时刻原子处在相干叠加态时的相对相位、相对强度与探测场和控制场的相对相位等对系统吸收特性及透明窗的影响.结果表明探测场与控制场的相对相位对吸收的影响与相干叠加态中两能级之间几率幅的相对相位对吸收的影响作用相反,系统在两下能级干涉极大时,存在一个很宽的透明带.应用缀饰态理论和量子相干理论对所得结果进行了解释.

Coherent control of the Electromagnetically Induced Transparency(EIT)was studied in inversed Y-type-four level system.Using the perturbation theory,the first-order perturbation solution of the system was derived,and the formula for width of the EIT window was obtained.Under the condition of the weak probing field,the effects of the controlling field intensity,coupling field intensity and the detunings on the EIT window were analyzed.It is found that the width of the EIT window broadens when the intensity of the control field increases,and narrows when the intensity of the coupling field increases.The EIT window width and the absorption for the probing field out the EIT window increase when the probing field and the coupling field are off the two-photon resonance.Under the condition of the weakly probing field and weakly control field,in the coherent superposition state,the effects of the original relative phases,relative intensities and relative phase between the probing field and control field on the absorption properties and EIT window width were analyzed.The results show that the effect of the relative phases between the probability amplitudes in the coherent superposition state on the absorption of the atom system is reverse to that the effect of the relative phases between the probing field and control field.The numerical results are elucidated by the dressed state theory and quantum coherence theory.