Method for quantum key generation from multiple receivers

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Solution Overview

Problem

Existing quantum key generation networks with multiple receivers face inefficiencies due to mutual interference and time-consuming comparisons, leading to lower quality and rate of quantum key generation, especially when aligning entanglement properties between multiple receivers.

Innovation Solution

A method and system for quantum key generation between at least four receivers using entangled photon pairs, where connections are established in time intervals, allowing independent comparisons of entanglement properties between two or more connections, and utilizing a frequency multiplexer and control device to align entanglement properties without interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If simultaneous comparison between multiple receivers is performed, then the number of comparison steps is reduced, but mutual interference occurs leading to lower quality and rate of quantum key generation

Engineering Contradiction:
Improvequantum key generation rateVSAvoidquality of connection
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent divides the quantum key generation process into multiple time intervals, where in each interval only two receivers are actively compared while others wait. This temporal segmentation eliminates mutual interference between comparisons, allowing high-quality alignment for each receiver pair while maintaining overall system productivity through parallel progression of multiple comparison sequences across different time intervals.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If all receivers are compared to a single reference frame, then the comparison process is simplified, but mutual interference occurs and time consumption increases

Engineering Contradiction:
Improvecomparison process complexityVSAvoidtime for comparison
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The patent segments the comparison process into multiple time intervals, where in each interval only two receivers are actively compared while others wait. This temporal segmentation eliminates mutual interference between comparisons, allowing high-quality alignment for each receiver pair while maintaining overall system productivity through parallel progression of multiple comparison sequences across different time intervals.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements periodic comparison cycles where different receiver pairs are compared in alternating time intervals. This periodic action allows systematic comparison of all receiver pairs without simultaneous interference, achieving complete alignment through multiple cycles while reducing total time consumption compared to sequential single-pair comparisons.

Inventive Principle:
Principle #19Periodic action

3Device complexity

If multiple receivers share the same fiber, then the network structure is simplified, but mutual interference during comparison occurs

Engineering Contradiction:
Improvenetwork structureVSAvoidquality of connection
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent divides the quantum key generation process into multiple time intervals, where in each interval only two receivers are actively compared while others wait. This temporal segmentation eliminates mutual interference between comparisons, allowing high-quality alignment for each receiver pair while maintaining overall system productivity through parallel progression of multiple comparison sequences across different time intervals.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary wavelength assignment and receiver pairing before the comparison process begins. By pre-organizing which receivers will be compared together in which time intervals, the system avoids mutual interference during fiber-shared comparison operations while maintaining the simplicity of the shared-fiber network structure.

Inventive Principle:
Principle #10Preliminary action

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

This approach enhances the generation rate and quality of quantum keys by optimizing connections for precise and fast alignment, reducing interference, and requiring fewer balancing devices, resulting in a more efficient and cost-effective network.

Implementation Method 1

Generation of entangled photon pairs in a source, wherein each photon pair comprises a signal photon and an idler photon, which are entangled with each other in an entanglement property

Methodology Applied
Scientific EffectEntanglement:

Implementation Method 2

the frequency multiplexer is arranged in or after the source, which is configured to divide the signal photons and idler photons according to their wavelength onto the quantum channels of the multiple receivers

Methodology Applied
Scientific EffectWavelength separation: Dispersion (of waves)

Implementation Method 3

each receiver has a detection module which has a measuring module and at least one detector, which are configured to detect the entanglement property of the photons for quantum key generation

Methodology Applied
Scientific EffectPhoton detection: Photoelectric Effect

Data Source

PatentEP4568172B1Method for quantum key generation from multiple receivers
Publication Date: 2025.11.12 QUANTUM OPTICS JENA GMBH
  • EP4568172B1 patent drawingFigure 1
  • EP4568172B1 patent drawingFigure 2~4
  • EP4568172B1 patent drawingFigure 5~6

AI summary

A method for quantum key generation using entangled photon pairs between at least four receivers (4) is proposed, comprising the following steps: i) generation of entangled photon pairs; ii) splitting the signal photons and the idler photons into quantum channels based on their wavelength and transmitting the signal photons and the idler photons via a splitter (6) and/or switch (7); iii) detection of the signal photons and the idler photons at the respective receivers (4); iv) quantum key generation between the receivers (4).It is essential that, for quantum key generation, several time periods are formed between all receivers (4), wherein steps i) to iii) are carried out in each time period, and that in each time period, before and/or during step ii), a comparison of the entanglement property is carried out only between two or more connections Vj, which can be compared independently of one another, and that the time periods differ in such a way that at least one connection Vj is exchanged for another connection Vj in order to carry out quantum key generation between all receivers (4) over the several time periods.