Cavity Field Spectrum for System Consisting of Cascade Three-level Atom within Kerr-medium Filled Cavity

A full quantum theory is applied to the investigation of the cavity field spectrum of a system containing the cascade three-level atom,initially in the most excited state,interacting with the single mode of a Kerr-medium filled cavity.The vacuum Rabi splitting of the system is found affected by Kerr nonlinearity,contrary to the two-level atom case.For an initial Fock-state field,the Kerr effects are mainly reflected by the asymmetry of the spectrum and a change in the number of spectral peaks if the coupling between the field and the Kerr medium is weak.The effects are also reflected by receding away from the resonant frequency of the central resonant peak in the absence of the Kerr medium if the field-medium coupling is strong.For an initial thermal field,the cavity spectrum can be a continuous band or discrete lines depending on the strength of the Kerr effect.