Nonlinear optical generation of time-delayed entanglement

A model is presented of nth order nonlinear processes in whispering gallery mode resonators, with scattering coherently coupling degenerate counter propagating modes. It is shown that such systems generate strong squeezing and time-delayed entanglement. The model can be generally applied to any pair of nonlinear coherently coupled cavities and is of particular relevance to whispering gallery mode resonators. A feature of the entanglement is that, by tuning the coherent coupling rate the peak entanglement can be tuned to occur away from the carrier frequency. This has technological significance allowing low frequency noise sources around the carrier frequency to be avoided. All-optical time-delayed entanglement has many applications, such as an all-optical quantum memory.