We have begun to study the quantum internet, discussing its importance, as well as its implementation in the near term. This discussion has included a high-level overview of the protocols we can implement on a quantum network, as well as the central role that quantum repeaters play in distributing entanglement, which is a fundamental task for the quantum internet.

In this module, we begin by taking a step back. Tim Coopmans will introduce the “one-time pad”, a simple yet powerful cryptographic protocol which uses shared randomness to achieve total privacy. He follows this with a discussion of the BB84 protocol, which generates shared randomness using the unique features of quantum mechanics. Afterwards, Filip Rozpedek will then discuss the difficulties in creating ideal entangled states between nodes. He introduces entanglement distillation, which can be used to filter out impure states in entanglement distribution processes. This module concludes with an opportunity for you to work out a simple example of entanglement distillation for yourself.

We hope you enjoy this detailed treatment of quantum networks.