Cavity-Induced Enhancement of Squeezing in Resonance Fluorescence of a V-Type Three-Level Atom

The quadrature squeezing spectra in the resonance fluorescence of a V-type three-level atom driven by a coherent field and coupled to a single-mode cavity is investigated. For weak excitation, the fluorescence field exhibit squeezing in the out-of-phase quadrature. The coupling between the atom and the cavity mode can greatly enhance the squeezing centred at the laser frequency. More importantly, for strong excitation, under the effect of the cavity-atom coupling, the in-phase quadrature of fluorescence can exhibit two-mode squeezing at the two inner sideband frequencies. By working in the dressed-state representation and hiring secular approximation, we give an analytical explanation for the effect. The result shows, under appropriate conditions, the squeezing can be greatly enhanced by appropriately tuning the cavity resonant frequency.