Studies Of Quantum Correlation Of The Fields In Phase Dependent Electromagnetically Induced Transparency

As the hotspot topic in quantum optics, atomic coherence effect has attracted a great deal of interest for recent years as inducing a series of important and interest-ing phenomena. Electromagnetically induced transparency and coherent population trapping are the topics of most concern. The common mechanism for them is dark state resonance. When two beams of optics fields interact with on Raman two-photon resonance with three level atoms in A configuration, the atoms will be trapped into a coherent superposition state, which usually called the dark state. The effect is usually named dark-state resonance effect. Typically electromagnetically induced transparency can take place in the three level atoms in A configuration, in which two resonance monochromatic fields are applied to the two wings. The controlled field is called the probe field, while the control field is named the pump field. On the con-dition of two-photon resonance, the medium are transparent for the fields with zero absorption. However, once the probe is not so weak compared with the pump field, the nonlinear response should be take into account. Studies show that it will lead to the oscillatory transfer of the initial quantum properties between the two fields. As current research only focuses on three level atoms in A configuration, we would be interested in four level atoms.In this paper, we consider an ensemble of N four-level atoms in in double A configuration, we apply three initial in a squeezed state probe fields and a initial in a coherent state pump field. Based on phase-dependent electromagnetically in-duced transparency, we calculate the stationary quadrature noise spectrum of the four comparable fields. It can be found that the initial coherent pump field get some squeezing, while the only probe field reduce some squeezing. There are transfer of quantum correlation between the probe fields and the pump fields. The amplitude of the oscillatory not only dependent on the relative intensity of the four fields, but on the choose of parameter.