On the effect of the number of photons on the generation and transfer of entangled states between toroidal cavities via artificial atoms

We present an efficient scheme for the generation of entangled states of two spatially separated whispering-gallery-mode (WGM) micro-resonators which are coupled via 2 two-level atoms. Using an atom chain as bridges, we explore the possibility of generation, transfer as well as distributing quantum entanglement between the two cavities. We show that, for an initial preparation with the system having only one photon, the atoms can become periodically (and maximally) entangled while the intra-cavity modes in each cavity become periodically (partially) entangled. Interestingly, if the cavities are initially prepared with two photons, the dynamics can be tuned in such a way that the intra-cavity modes in each cavity become periodically entangled, reaching maximum entanglement, while the atoms remain unentangled during all time.