Category:Trusted Repeater Network Stage

Quantum repeaters are used to transmit quantum information over long dis- tances. Quantum channels are inherently lossy. Hence to reach longer dis- tances, intermediate nodes called quantum repeaters are necessary. These repeaters are placed at calculated intervals along the quantum channel, allow- ing qubits to be transmitted over arbitrarily long distances. In its simplest form, a quantum repeater works by �rst generating entanglement between the repeater and each of the end nodes individually. This stage has the functionality of forming a trusted repeater network, hav- ing at least two end nodes. The two ends can receive quantum-generated codes but cannot send or receive quantum states as end-to-end transmission of qubits is not allowed. Any two end users can share an encryption key and here the trusted repeater would have access to keys as well. Each pair of adjacent nodes uses Quantum Key Distribution (link here) to exchange encryption keys. These pairwise keys allow the end nodes to generate their own key, provided that all intermediary nodes are trusted. The �rst step towards upgrading these networks could be measurement deviceindependent QKD (link here), which is a QKD protocol that is secure even with un-trusted measurement devices.