Simulations show gains with a hybrid quantum repeater chain

Researchers at the Okinawa Institute of Science and Technology, in collaboration with LQUOM, Inc., are simulating a quantum repeater chain design that integrates atom-based quantum processing units with spontaneous parametric down-conversion photon sources and atomic frequency comb quantum memories. The proposed design uses the strong spectro-temporal multiplexing capability of the quantum memory to enable high-rate elementary-link entanglement generation between repeater nodes. This efficient hybrid architecture addresses the difficulties of realizing quantum repeaters despite inherent device constraints, and simulations demonstrate advantages for end-to-end secret key rates in a linear repeater-chain model. This hybrid architecture distinguishes itself through substantially enhanced multiplexing capability, circumventing limitations found in purely atom-based systems where entanglement generation is restricted by the number of emitters within the quantum processing unit. The proposed repeater first generates photonic entanglement remotely in a heralded manner before transferring it to the quantum processing units. This separation of stages…