Quantum Network Clock Synchronization With Loop Attack Detection

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Solution Overview

Problem

Existing quantum communication networks face challenges in expanding point-to-point, two-node systems to multi-node networks for secure clock synchronization and syntonization, as existing methods do not address synchronization across three or more nodes without treating the network as a cluster of two-node networks.

Innovation Solution

A multi-node quantum communication network with three or more nodes connected via authenticated channels, utilizing polarization-entangled photon pairs and a controller to ensure secure time transfer and syntonization by detecting malicious party attacks through loop closure constraints and asymmetry manipulation detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If point-to-point two-node quantum communication systems are used, then secure time transfer can be achieved between two nodes, but the system cannot be expanded to multi-node networks for comprehensive clock synchronization

Engineering Contradiction:
Improvenetwork scalabilityVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the multi-node quantum network into multiple two-node quantum subsystems, where each subsystem maintains secure time transfer independently. By dividing the complex multi-node synchronization problem into manageable pairwise segments, the system achieves network scalability while controlling complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a universal quantum communication protocol that functions effectively for both two-node and multi-node configurations. The same quantum time transfer mechanism serves multiple purposes: pairwise clock synchronization between any two nodes and comprehensive network-wide syntonization, eliminating the need for different systems at different scales.

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

2Reliability

If multi-node quantum networks are implemented without loop closure constraints, then network expansion is possible, but malicious party attacks cannot be detected

Engineering Contradiction:
Improveattack detection capabilityVSAvoidnetwork configuration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements loop closure constraints that create feedback mechanisms within the quantum network. By establishing closed loops of quantum time transfer paths and monitoring for asymmetries in photon arrival times, the system continuously feedbacks on potential attacks. This feedback enables detection of malicious interference while maintaining a manageable network configuration through systematic loop monitoring.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent exploits temporal asymmetry in photon arrival times as a detection mechanism. By comparing forward and backward propagation times in quantum loops, the system identifies asymmetric deviations that indicate malicious attacks. This asymmetry-based detection enhances reliability by providing clear attack signatures without requiring overly complex network configurations.

Inventive Principle:
Principle #4Asymmetry

3Reliability

If clock synchronization is performed across multiple nodes, then network-wide time coordination is achieved, but vulnerability to malicious interference increases

Engineering Contradiction:
Improvesynchronization securityVSAvoidmalicious interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by pre-establishing loop closure constraints and asymmetry thresholds before malicious attacks can occur. These pre-configured security parameters create defensive boundaries that automatically counteract or detect malicious interference attempts, enhancing synchronization security while monitoring for harmful factors across the network.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The patent introduces loop closure constraints as intermediary verification mechanisms between clock synchronization operations and malicious attacks. These constraints act as mediators that validate time transfer accuracy across multiple nodes, providing an additional layer of security that filters out malicious interference while maintaining legitimate synchronization operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables secure, non-spoofable clock synchronization and syntonization across multiple nodes, protecting against malicious interference by constraining asymmetry manipulations, ensuring network security and accuracy.

Implementation Method 1

utilizing polarization-entangled photon pairs

Methodology Applied
Scientific EffectPolarization entanglement: Polarisation

Data Source

PatentEP4150538B1Quantum secure network clock synchronization
Publication Date: 2026.02.18 XAIROS SYST INC
  • EP4150538B1 patent drawingFigure 1
  • EP4150538B1 patent drawingFigure 2
  • EP4150538B1 patent drawingFigure 3~4

AI summary

A multi-node, quantum communication network for providing quantum-secure time transfer with Damon attack detection is described. The network includes three or more nodes connected via authenticated communication channels forming a closed loop. By determining differences between the local times at as well as the time durations required for photons to travel between the three or more nodes, the network detects a Damon attack, if present. For example, the network imposes a closed loop condition to detect the Damon attack. The network can also use the local time differences and time durations for photon travel between nodes to synchronize the local clocks at the three or more nodes of the network.