Waveplate Pulse Division for High-Speed Quantum Security

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Solution Overview

Problem

Existing quantum communications systems face a disconnect between security and speed, with conventional systems being vulnerable to quantum attacks and state-of-the-art systems operating orders of magnitude slower than required for efficient insertion into optical communication networks, while physical layer security protocols are limited by opto-mechanical components and channel conditions.

Innovation Solution

A quantum communications system incorporating a pulse transmitter, pulse divider with staged birefringent crystals, and a pulse recombiner with conjugate waveplates to divide and recombine quantum pulses, enabling secure data transmission using a hybrid approach with conventional off-the-shelf detectors, maintaining high data rates and security by placing multiple photons in a superposition state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If quantum communications systems use single photons for information transmission, then security is improved through quantum mechanics principles, but data transmission speed deteriorates to orders of magnitude slower than conventional systems

Engineering Contradiction:
ImprovesecurityVSAvoiddata transmission speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system divides each optical pulse into multiple time bins, placing multiple photons into a superposition state across these bins. This segmentation allows the system to maintain quantum security properties while increasing the information capacity per pulse, thereby improving data transmission speed without sacrificing security

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the parameter of photon number per pulse from single photon to multiple photons in superposition state. By using pulse division and creating superposition states across multiple time bins, the system transforms the quantum state parameters to enable higher data rates while maintaining the quantum mechanical security guarantees

Inventive Principle:
Principle #35Parameter changes

2Productivity

If quantum communications systems operate at high data rates for network insertion, then productivity is improved, but security deteriorates due to vulnerability to quantum attacks and channel interference

Engineering Contradiction:
Improvedata rateVSAvoidsecurity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary pulse division and superposition state creation at the transmitter before transmission. By pre-establishing the quantum superposition state across multiple time bins, the system enables high data rates while the quantum state itself provides inherent security against eavesdropping and quantum attacks

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention uses optical pulses divided into multiple time bins as an intermediary carrier. This pulsed superposition state acts as a mediator that carries quantum information at high rates while the distributed quantum state across time bins provides security through quantum mechanics, protecting against both quantum attacks and channel interference

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If physical layer security protocols are implemented, then security is improved, but device complexity increases due to opto-mechanical components and channel condition requirements

Engineering Contradiction:
ImprovesecurityVSAvoidopto-mechanical components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention replaces complex opto-mechanical security components with a purely optical pulse division and superposition approach. By using staged birefringent crystals and linear optical elements to create and detect quantum superposition states, the system achieves physical layer security without requiring moving mechanical parts, thereby reducing device complexity while maintaining security

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

The system achieves secure data transmission with Gbps data rates over distances exceeding 100 kilometers, providing a quantum layer of security by scrambling bit streams and maintaining image reconstruction despite link loss, outperforming single photon systems and conventional optical systems in terms of information security and efficiency.

Implementation Method 1

at least one waveplate upstream from the pulse divider and configured to alter a polarization state of pulses travelling therethrough

Methodology Applied
Scientific EffectPolarization rotation: Polarisation

Implementation Method 2

A pulse divider downstream from the pulse transmitter is configured to divide each pulse having a plurality of X photons into a plurality of Y time bins with Y>X

Methodology Applied
Scientific EffectBirefringence: Birefringence

Data Source

PatentEP4178123B1Quantum communications system having at least one waveplate to alter pulse polarization and associate methods
Publication Date: 2025.08.06 EAGLE TECHNOLOGY LLC
  • EP4178123B1 patent drawingFigure 1
  • EP4178123B1 patent drawingFigure 2
  • EP4178123B1 patent drawingFigure 3

AI summary

A quantum communications system may include a transmitter node, a receiver node, and a quantum communications channel coupling the transmitter node and receiver node. The transmitter node may include a pulse transmitter, a pulse divider downstream from the pulse transmitter, and at least one first waveplate upstream from the pulse divider and configured to alter a polarization state of pulses travelling therethrough. The receiver node may include at least one second waveplate being a conjugate of the at least one first waveplate, a pulse recombiner upstream from the at least one second waveplate, and a pulse receiver downstream from the at least one second waveplate.