Scheme for generating distillation-favorable continuous-variable entanglement via three concurrent parametric down-conversions in a single X(2) nonlinear photonic crystal

We propose to generate a single-mode-squeezing two-mode squeezed vacuum state via a single X (2) nonlinear photonic crystal. The state is favorable for existing Gaussian entanglement distillation schemes, since local squeezing operations can enhance the final entanglement and the success probability. The crystal is designed for enabling three concurrent quasi-phase-matching parametric-down conversions, and hence relieves the auxiliary on-line bi-side local squeezing operations. The compact source opens up a way for continuous-variable quantum technologies and could find more potential applications in future large-scale quantum networks.