Quantum State Wavelength Routing for Low Loss Communication

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Solution Overview

Problem

Existing quantum communication networks face challenges in routing quantum states to multiple users efficiently, as static systems result in low communication rates due to wavelength splitting, while dynamic systems with optical routers incur high losses.

Innovation Solution

A method and system utilizing an entangled photon pair source connected to a router via a multi-wavelength quantum channel, allowing dynamic wavelength adjustment to allocate quantum states specifically to receivers, enabling high communication rates without splitting the wavelength spectrum.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If static point-to-point quantum communication systems use wavelength multiplexing to serve multiple receivers, then the system can support multiple users, but the single photon rate to each receiver decreases leading to low communication rates

Engineering Contradiction:
Improveability to serve multiple receiversVSAvoidcommunication rate
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent transforms the static wavelength assignment into a dynamic system where the source can actively select and change wavelengths based on which receiver should be served. The source dynamically adjusts the quantum state wavelength to match the desired receiver's channel, enabling flexible routing without splitting the spectrum. This dynamic wavelength selection resolves the contradiction by allowing the system to serve multiple receivers sequentially at full rate rather than simultaneously at reduced rates.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If electrically controlled optical routers are used to enable dynamic addition or removal of receivers, then the system becomes flexible and adaptable, but high losses occur in the routing process

Engineering Contradiction:
Improvedynamic addition or removal of receiversVSAvoidrouting losses
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent extracts the routing function from the traditional optical router and relocates it to the quantum state source. Instead of using a separate router component that introduces losses, the source itself generates quantum states at the appropriate wavelengths to directly route to the desired receiver. This extraction of the routing function eliminates the need for lossy intermediate routing components while maintaining dynamic adaptability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses the wavelength of the quantum state as an intermediary carrier of routing information. Rather than using physical switches or routers to direct quantum states to different receivers, the wavelength itself encodes the destination information, and the quantum channel acts as the medium that naturally routes different wavelengths to different receivers without active switching components that would introduce losses.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the broad spectrum of the source is split according to the number of receivers, then wavelength multiplexing is achieved, but the single photon rate transmitted to each receiver becomes low

Engineering Contradiction:
Improvewavelength multiplexing capabilityVSAvoidsingle photon rate
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The system dynamically selects which wavelength channel to use based on the intended receiver, rather than statically splitting the broad spectrum. The source generates quantum states at full intensity on a single wavelength at a time, and the wavelength selection is dynamically changed to serve different receivers. This maintains high single photon rates because the full spectral power is concentrated on one channel at a time rather than divided among multiple channels simultaneously.

Inventive Principle:
Principle #15Dynamics

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 achieves high communication rates between receivers with minimal losses, allowing for flexible addition of new receivers without altering the source or router components, by using the entire wavelength spectrum effectively.

Implementation Method 1

generation of a quantum state in the source and transmission of the quantum state to the router, whereby the quantum state is an entangled photon pair with a signal photon and an idler photon

Methodology Applied
Scientific EffectSpontaneous parametric down-conversion:

Data Source

PatentEP4160976B1Low loss routing for quantum communication
Publication Date: 2025.03.26 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP4160976B1 patent drawingFigure 1
  • EP4160976B1 patent drawingFigure 2
  • EP4160976B1 patent drawingFigure 3

AI summary

It is claimed a method of low loss routing for quantum communication, comprising a single photon source (1) and/or a weak coherent light source (1) for decoy state quantum key distribution, a router (3), two or more receivers (5), and a quantum network connecting each receiver (5) via a quantum channel (4) with the router (3), whereby the method comprises the steps i) generation of a quantum state in the source (1) and transmission of the quantum state to the router (3), whereby the quantum state is a single photon and/or a weak coherent light pulse; ii) allocation of the quantum state based on the wavelength of the quantum state to a quantum channel (4) by the router (3); iii) transmission of the quantum state via the quantum channel (4) to a receiver (5); iv) detection of the quantum state at the receiver (5) in order to establish a quantum communication between the source (1) and the receiver (5); According to the invention the source (1) comprises a modification means (2), and the source (1) is connected with the router (3) via a multi-wavelength quantum channel (6), and the modification means (2) set the wavelength of the generated quantum state in step i) in order to enable a specific allocation of the quantum state in step ii) to a specific quantum channel (4) to a specific receiver (5), in order to enable a quantum communication between the source (1) and the specific receiver (5).