Optical Bypass for Quantum Key Distribution

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Solution Overview

Problem

Existing optical communication networks face challenges in efficiently transporting encryption keys, including quantum keys, as conventional methods result in the loss of valuable resources and unsuitable conditions for preserving the state of quantum keys during transmission.

Innovation Solution

An all-optical path is created for transferring encryption keys or information as a stream of single photons, bypassing amplification and non-optical sections, using optical bypass sections and switches to enable end-to-end optical transfer without intermediate termination, utilizing wavelengths typically used by signalling channels like the OSC, and employing CV-QKD to maintain resilience against noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If quantum keys are transmitted through conventional optical communication networks with amplification and non-optical sections, then the network infrastructure can be utilized, but the quantum key state is degraded or lost due to intermediate electrical conversion and noise

Engineering Contradiction:
Improvequantum key state preservationVSAvoidnetwork infrastructure requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The optical communication network is segmented into distinct functional sections: quantum key transmission paths that bypass amplification and non-optical sections, and conventional data transmission paths that use standard amplification. This segmentation allows quantum keys to travel through dedicated all-optical channels without degradation while maintaining the benefits of conventional network infrastructure for other traffic.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Optical bypass sections and optical switches serve as intermediaries to route quantum key signals around amplification and non-optical sections. These intermediary components enable the quantum signals to traverse the network infrastructure without direct interaction with the degrading elements, preserving the quantum state while still utilizing the overall network structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If quantum keys are transmitted using all-optical paths bypassing amplification and non-optical sections, then the quantum key state is preserved, but additional optical bypass hardware is required

Engineering Contradiction:
Improvequantum key state preservationVSAvoidoptical bypass hardware
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The optical bypass sections and optical switches are designed to serve multiple functions: routing quantum key signals during quantum communication modes and routing conventional optical signals during standard data transmission modes. This multi-functionality reduces the need for dedicated hardware solely for quantum bypass, as the same infrastructure components handle both quantum and classical traffic depending on operational requirements.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The network dynamically switches between conventional transmission mode and quantum bypass mode based on traffic requirements. Optical switches enable flexible reconfiguration of signal paths, allowing the system to adapt to different operational states and utilize the same physical infrastructure for both quantum key distribution and conventional data transmission without permanent dedicated hardware for each function.

Inventive Principle:
Principle #15Dynamics

3Length of stationary object

If conventional optical amplification is used for signal boosting, then transmission distance is extended, but quantum key integrity is compromised due to noise and electrical conversion

Engineering Contradiction:
Improvetransmission distanceVSAvoidquantum key integrity
Core Design Contradiction:
Length of stationary objectVSReliability

Solution Approach 1:

The transmission path is segmented into quantum-sensitive sections that bypass amplification and conventional sections that use standard amplification. By segmenting the network this way, quantum keys can be transmitted over extended distances through the bypass paths without exposure to amplification-induced noise and degradation, while still achieving long-distance communication capabilities.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Optical bypass sections act as intermediary transmission channels that extend the effective transmission distance for quantum keys without requiring conventional amplification. These intermediary paths allow quantum signals to travel longer distances by avoiding the noise-generating amplification process entirely, maintaining integrity while achieving extended range through dedicated all-optical routing.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3596858B1Quantum key distribution in optical communications network
Publication Date: 2023.09.27 BRITISH TELECOM PLC
  • EP3596858B1 patent drawingFigure 1~2a
  • EP3596858B1 patent drawingFigure 2b
  • EP3596858B1 patent drawingFigure 3

AI summary

A method for operating a communications network node; in which the node comprises a first amplified optical section and a second non-optical section; in which the method comprises: receiving at the node, a first optical channel at a first wavelength and a second optical channel at a second wavelength; directing the first optical channel to the first amplified optical section; in which the node further comprises an optical bypass section; in which the method further comprises: directing the second optical channel to the second non-optical section during a first time period and directing the second optical channel to the optical bypass section during a second time period.