Quantum Key Distribution System Using Quantum Repeaters

A quantum repeater is introduced as an intermediary component between terminal nodes to extend spatial distance without compromising security. The quantum repeater maintains quantum states through entanglement swapping and purification, avoiding the need to digitize quantum encryption keys at intermediate trusted nodes, thus preventing unauthorized access while extending the system's spatial coverage.

The patent replaces the classical mechanical approach of digitizing and forwarding quantum encryption keys through trusted nodes with a quantum mechanical approach using quantum repeaters. These repeaters utilize quantum entanglement and quantum state manipulation to extend transmission distance while maintaining the quantum nature of the keys, eliminating the security vulnerability inherent in digitization.

The quantum repeater acts as a secure intermediary that handles key management operations without requiring digitization. It performs quantum state manipulation, entanglement swapping, and purification operations that maintain the quantum nature of encryption keys throughout the forwarding process, preventing unauthorized reading while enabling efficient key management across distributed nodes.

The patent changes the fundamental parameter of key representation from classical digital form to quantum mechanical form. By maintaining keys in quantum states (superposition, entanglement) rather than digitized form, the system enables automated key management operations while preventing unauthorized access, as any measurement or reading of the quantum state would collapse it and be detectable.

Quantum repeaters serve as specialized intermediaries that extend spatial coverage without introducing the performance degradation associated with classical trusted nodes. By utilizing quantum entanglement and avoiding digitization, they eliminate the need for complex security protocols and key management operations at each intermediate point, maintaining high system performance even as spatial distance increases.

The patent segments the quantum key distribution system into multiple quantum repeater units that can be distributed over long distances. Each repeater unit operates independently using quantum entanglement, allowing the system to extend spatial coverage by adding segments without proportionally increasing the attack surface, as each segment maintains quantum security properties.