Quantum Key Distribution Wavelength Routing Multi-User Network
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Solution Overview
Problem
Existing quantum key distribution systems over networks face challenges in establishing secure, efficient communication between specific users due to broadcasting signals to all receivers, lack of synchronization, and inability to identify intended recipients, especially in multi-user wavelength division multiplexing networks.
Innovation Solution
A communication system employing wavelength routing technology with distinct receiving-wavelengths for each receiver, using an array waveguide grating for demultiplexing, and differential phase detection to ensure secure and efficient quantum key distribution between a transmitter and selected receivers over a multi-user WDM network, utilizing continuous wave light and random phase modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If quantum key distribution is implemented over a multi-user WDM network using conventional star network configuration, then multiple receivers can simultaneously receive signals, but the system cannot identify which user is the intended receiver and all users receive signals even if not intended
Solution Approach 1:
The patent segments the broadcast signal by wavelength, assigning each receiver a unique receiving-wavelength. The wavelength routing demultiplexer separates the quantum key signals at different wavelengths to specific receivers, ensuring that only the intended receiver processes each signal. This resolves the contradiction by maintaining multi-user capability while preventing information loss through proper signal routing.
Solution Approach 2:
The patent introduces a wavelength routing demultiplexer as an intermediary device between the transmitter and receivers. This intermediary routes quantum key signals to the correct receiver based on wavelength matching, solving the problem of identifying intended recipients in a multi-user network without compromising security or signal integrity.
2Ease of operation
If quantum key distribution uses phase modulation with synchronization requirements, then encoding and decoding can be achieved, but receivers need complex synchronization with sent pulses
Solution Approach 1:
The patent employs differential phase detection where each receiver compares the phase of consecutive pulses locally without needing external synchronization signals. The receiver independently determines phase differences between pulses, making the system self-synchronizing and eliminating complex synchronization mechanisms while maintaining ease of operation for encoding and decoding.
3Reliability
If quantum key distribution is performed over optical fiber networks with temperature variations, then communication can be maintained, but temperature shifts and phase shifts affect system stability
Solution Approach 1:
The patent uses differential phase detection that dynamically adapts to temperature and phase variations by measuring phase differences between consecutive pulses rather than relying on absolute phase references. This dynamic approach compensates for environmental changes, maintaining both communication reliability and phase stability in varying temperature conditions.
4Reliability
If conventional cryptographies are used, then communication can be established, but ultimate security cannot be achieved
Solution Approach 1:
The patent integrates quantum key distribution with conventional WDM network infrastructure, allowing the system to leverage existing optical fiber networks and wavelength routing technologies. This multi-functionality approach achieves ultimate security through quantum mechanics while avoiding excessive complexity by reusing proven conventional network components.
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 and efficient quantum key distribution by routing quantum signals to specific receivers, overcoming broadcasting issues and temperature/phase shift variations, with high communication efficiency and practical application potential.
Implementation Method 1
a multi-user WDM network with wavelength routing... a wavelength routing technology is employed... realized by a wavelength division demultiplexer, which may be in the form of an array waveguide grating (AWG)
Implementation Method 2
differential phase detection is also employed in the present invention, in order to overcome the influence of a temperature shift and phase shift in the system
Implementation Method 3
the present invention employs a randomly phase-modulated light of weak coherent states, e.g. two non-orthogonal states with phase shifts 0 and x
Data Source
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AI summary
A system and a method for quantum key distribution over a multi-user wavelength division multiplexing (WDM) network are disclosed. The system comprises a tunable or multi-wavelength transmitter; a plurality of receivers, each assigned a receiving-wavelength; and a multi-user WDM network linking the transmitter to the receivers. The transmitter can select a receiver among the receivers to be communicated therewith and transmit quantum signals to the selected receiver over the WDM network. The quantum signals are at a wavelength equal to a receiving-wavelength of the receiver. Therefore the WDM network allows quantum signals to be communicated between the transmitter and the receivers by wavelength routing.