Multimode thermal-seeded parametric down-conversion: Entanglement and ghost imaging

We analyze a frequency degenerate two-arm seeded downconversion process in which the seed fields are spatially multimode chaotic fields. We prove that the output state exhibits a transition from entanglement to separability as far as the intensities of the seeds increase, whereas it is suitable for a ghost imaging experiment irrespective of its entanglement properties. Furthermore we present two experiments of ghost imaging with good visibilty based on parametric downconversion seeded on a single arm.