Transfer of spin squeezing and particle entanglement between atoms and photons in coupled cavities via two-photon exchange

摘要

We examine transfer of particle entanglement and spin squeezing betweenatomic and photonic subsystems in optical cavities coupled by two-photonexchange. Each cavity contains a single atom, interacting with cavity photonswith a two-photon cascade transition. Particle entanglement is characterized byevaluating optimal spin squeezing inequalities, for the cases of initiallyseparable and entangled two-photon states. It is found that particleentanglement is first generated among the photons in separate cavities and thentransferred to the atoms. The underlying mechanism is recognized as aninter-cavity two-axis twisting spin squeezing interaction, induced bytwo-photon exchange, and its optimal combination with the intra-cavityatom-photon coupling. Relative effect of non-local two-photon exchange andlocal atom-photon interactions of cavity photons on the spin squeezing andentanglement transfer is pointed out.