Efficient <i>In Situ</i> Generation of Photon-Memory Entanglement in a Nonlinear Cavity

Parametrically driving an optical cavity that simultaneously couples to an atomic ensemble quantum memory enables in situ generation of multimode photon-memory entanglement. A high-rate bipartite photon-memory entanglement can be generated even after discarding one entangled optical mode. This protocol can be realized with existing technologies based on photonic resonators integrated with a rare-earth-ion doped quantum memory. The proposed scheme shows significant advantages in entanglement generation rates compared with prevailing quantum memory protocols and experiments, with theoretical ebit rates of tens of MHz without fine-tuned operating conditions. Such a photon-memory entanglement source offers a versatile resource for quantum networking and interconnect applications.