Quantum repeater

A quantum repeater is a device designed to extend the range of quantum communication by creating entanglement across long distances without directly transmitting fragile quantum states. It works by establishing entanglement between adjacent nodes, then performing Entanglement swapping to connect distant nodes. Unlike classical repeaters, which amplify signals, quantum repeaters cannot amplify quantum states due to the No-Cloning Theorem. They require Quantum memory to store entangled states while classical communication coordinates the swapping protocol.

The absence of practical quantum repeaters is the single greatest bottleneck preventing a Quantum internet from emerging beyond laboratory demonstrations.