Quantum Key Distribution With Dynamic Optical Line Switching

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Solution Overview

Problem

Conventional quantum key distribution systems face challenges in selecting an optical transmission line with higher encryption key generation speed due to factors like crosstalk, fiber bending, fiber vibration, optical loss, and external light intrusion, which affect the detection accuracy of quantum signal channels.

Innovation Solution

Implementing a quantum key distribution system with switch units that can dynamically select between multiple optical transmission lines based on encryption key generation speed measurements, allowing for the selection of the most optimal line for quantum and classical signal channels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single optical transmission line is used for quantum key distribution, then the system structure is simple, but the encryption key generation speed is limited and cannot be optimized

Engineering Contradiction:
Improveencryption key generation speedVSAvoidtransmission line configuration
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the transmission line selection changeable and adaptive. Switch units are introduced to dynamically select different transmission lines based on real-time detection of encryption key generation speeds, transforming the static single-line configuration into a dynamic multi-line selectable system that can adapt to changing conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of transmission line selection from fixed to variable. By detecting encryption key generation speeds as a parameter and using this information to select optimal transmission lines, the system transforms a static configuration into one that actively adjusts based on measured performance parameters.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If multiple optical transmission lines are available for selection, then the encryption key generation speed can be optimized, but the system complexity increases

Engineering Contradiction:
Improveencryption key generation speedVSAvoidtransmission line selection
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent implements self-service by enabling the system to automatically detect encryption key generation speeds and select optimal transmission lines without manual intervention. The switch units and detection mechanisms work autonomously to monitor performance and make selection decisions, eliminating the need for operators to manually configure or evaluate multiple transmission lines.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent applies feedback by using detected encryption key generation speeds as feedback signals to guide transmission line selection. The system continuously monitors the performance parameter and uses this feedback information to adjust and select the optimal transmission line, creating a closed-loop control system that automatically optimizes performance.

Inventive Principle:
Principle #23Feedback

3Productivity

If transmission lines are fixed without switching capability, then the system is stable and simple to operate, but the encryption key generation speed cannot be maintained or improved under varying conditions

Engineering Contradiction:
Improveencryption key generation speedVSAvoidtransmission line adaptability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent transforms the static transmission line configuration into a dynamic system with switching capability. The switch units enable the system to adapt between different transmission lines based on detected encryption key generation speeds, providing the adaptability needed to respond to varying conditions while maintaining system stability through automated control.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4622166A1Quantum key distribution system, quantum key distribution device, and quantum key distribution method
Publication Date: 2025.09.24 KK TOSHIBA
  • EP4622166A1 patent drawingFigure 1
  • EP4622166A1 patent drawingFigure 2
  • EP4622166A1 patent drawingFigure 3

AI summary

A quantum key distribution system according to an arrangement includes a transmission device configured to transmit a photon to be used for generating an encryption key in quantum key distribution; and a reception device configured to receive the photon. The transmission device includes a quantum signal transmission unit configured to transmit the photon as a quantum signal. The reception device includes a quantum signal reception unit configured to receive the quantum signal. The quantum key distribution system further includes a first switch unit configured to select a transmission line for transmitting the quantum signal from a plurality of transmission lines; and a second switch unit configured to select the transmission line for receiving the quantum signal from the plurality of transmission lines.