QKD Cascaded Network Loop-Back Optical Switch
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Solution Overview
Problem
In quantum key distribution (QKD) network systems, the reliance on trusted relays for secure key transport and message transmission poses security risks, as these relays must be physically secured and trusted by all users, and there is a need for diagnostic checks without external interference.
Innovation Solution
A QKD cascaded network with loop-back capability, featuring optical switches in each relay for internal diagnostic measurements and pass-through communication, allowing secure diagnostic testing and bypassing of failed relays without external access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trusted relays are used for secure key transport in QKD networks, then security is improved, but device complexity and cost increase due to physical security requirements
Solution Approach 1:
The patent extracts the diagnostic and testing functionality from the external network environment and places it inside the relay station enclosure. By using optical switches to create loop-back paths, the system can perform self-diagnosis without requiring external physical access or trusted relay intervention, thereby reducing the physical security burden on relay stations while maintaining security through the trusted relay architecture.
Solution Approach 2:
The optical switch acts as an intermediary device that enables internal diagnostic measurements by creating a loop-back path. This intermediary allows the system to test QKD stations internally without external interference, mediating between the need for security and the need for diagnostic capability.
2Measurement precision
If external diagnostic testing is performed on QKD relays, then measurement capability is improved, but security deteriorates due to external access and interference risks
Solution Approach 1:
The patent extracts the diagnostic function from external access and relocates it within the relay station enclosure. Optical switches create internal loop-back paths that allow complete diagnostic testing of QKD stations without external physical access, thereby maintaining security while enabling precise measurement and diagnostic capabilities.
3Reliability
If failed relays are included in the network path, then network redundancy is improved, but productivity decreases due to key rate reduction
Solution Approach 1:
The patent implements dynamic reconfiguration capability through optical switches that can adapt the network topology in real-time. When a relay fails, the system can dynamically switch paths to bypass the failed relay, maintaining network redundancy while preserving high key rates through the alternative path. This dynamic adaptability resolves the contradiction between having redundant paths and maintaining high productivity.
Data Source
AI summary
A quantum key distribution (QKD) cascaded network with loop-back capability is disclosed. The QKD system network includes a plurality of cascaded QKD relays each having two QKD stations Alice and Bob. Each QKD relay also includes an optical switch optically coupled to each QKD station in the relay, as well as to input ports of the relay. In a first position, the optical switch allows for communication between adjacent relays and in a second position allows for pass-through communication between the QKD relays that are adjacent the relay whose switch is in the first position.