Chapter 10 - Quantum networking

Abstract

This chapter discusses how to build a quantum network. Basic concepts of quantum communication networks and the quantum Internet are introduced, followed by quantum teleportation and relay concepts. Then entanglement distribution, a key technique that enables quantum networking by employing quantum teleportation concepts, is described, starting with a brief description of how to generate entangled states. Entanglement swapping, Bell state measurements, and the Hong–Ou–Mendel effect are described, followed by continuous-variable (CV) quantum teleportation and then quantum network coding basics. The section after that is devoted to the engineering of entangled states by photon addition and subtraction. After describing photon subtraction and addition concepts, we discuss how to apply them to build a hybrid CV–discrete-variable (DV) quantum network. Hybrid quantum networks are described in terms of hybrid DV–CV entangled states as well as state teleportation and entanglement swapping through entangling measurements. The generation of entangled macroscopic light states is then discussed, given that macroscopic light states are much more tolerant of channel loss than discrete-variable states. The section ends with noiseless amplification as a possible approach to extend transmission distances between quantum nodes. The focus of the chapter then moves to cluster state-based quantum networking. The cluster states concept is introduced first, followed by cluster state processing. The same section describes cluster state-based quantum networking as both quantum Internet and distributed quantum computing enabling technology. The section that follows describes surface code-based and quantum low-density parity-check code-based quantum networking concepts. The final section relates to entanglement-assisted communication networks.