Quantum Repeaters and Memories: Basics and Applications

This lecture by Mikael Afzelius covers the fundamentals of quantum repeaters and memories, focusing on spin-photon entanglement, quantum teleportation, and light-matter interactions. Topics include quantum memories for photons, multimode storage, rare-earth-ion ensembles, coherent light-matter interactions, and the Bloch sphere representation. The lecture also delves into the practical aspects of quantum repeaters, such as entanglement swapping and the use of multimode quantum memories to overcome rate limitations. Additionally, the discussion extends to the criteria for efficient quantum memories, including success probability and fidelity. The presentation concludes with insights into time multiplexing in rare-earth memories and the importance of coherent light-matter interactions in quantum information processing.