Quantum communication, repeaters, qubit amplifiers and large entanglement (Prof. N. Gisin)

On the fundamental side, quantum communication is fascinating because it illustrates the power of entanglement and of non-local quantum correlations. On the application side, quantum communication is already relatively advanced with Quantum Random Number Generators and Quantum Key Distribution (QKD) systems having found niche markets. On the academic research side quantum communication has still a long way to go until a functional quantum repeater can extend the distances to continental scales. Quantum repeaters are based on quantum teleportation, the most fascinating application of entanglement. Additionally, quantum repeaters require quantum memories with memory times close to a second; this represents one grand challenge for quantum communication. Entangling two quantum memories, that is two crystal, raises the fascinating question of “what is large entanglement?”.