Physical and architectural considerations in quantum repeaters
Mohsen Razavi, K. Thompson, Hamid Farmanbar, Marco Piani, Norbert Lütkenhaus · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2008
Quantum repeaters enable us to distribute entanglement between remote parties by relying on a network of quantum memory units that exhibit efficient coupling to light, scalability, and long coherence times. Entanglement is initially distributed between nearest neighbors and then extended to the far-end nodes using entanglement swapping techniques. For real-time applications, such as quantum key distribution, the above tasks must be repeated successively, according to a proper protocol, to generate entangled states at a certain rate. This paper studies a number of such protocols and the interplay between the rate of entanglement generation, the number of employed memories, and the coherence time of memory units.