Quantum-Squeezing-Engineered Third-Order Kerr Nonlinearity and Optical High-Order Sideband Comb in a Composite Resonator-Atom System

Optical microresonators can greatly enhance light-matter interactions and reduce the power necessary to observe nonlinear optical effects. Manipulation and application of atom-resonator-coupling-induced strong nonlinearity have received much attention in recent years. Here, we present a scheme to realize quantum-squeezing-engineered third-order Kerr nonlinearity and optical high-order sideband comb in a composite system consisting of a two-level atom and two directly coupled whispering-gallery-mode optical microresonators. By quantum squeezing one of two coupled resonator modes in this system, the effective resonator-resonator and atom-resonator coupling rates as well as the frequency of the squeezed resonator mode can be effectively controlled. Based on this mechanism, we show that the Kerr nonlinearity of the composite system can be effectively engineered by using the resonator-mode squeezing when the system is monochromatically driven beyond the weak-excitation limit. On the other hand, when the composite system is bichromatically driven, the optical high-order sideband combs formed in the transmission spectra of the system can also be effectively engineered by the resonator-mode squeezing. Therefore, our scheme provides a novel mechanism to control the physical properties of composite resonator-atom systems for various applications, and demonstrates that optical nonlinear effects induced by the atom-resonator coupling can be effectively engineered via quantum squeezing.