Active Combiner for QKD WDM Noise Management
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Solution Overview
Problem
In Quantum Key Distribution (QKD) systems using Wavelength Division Multiplexing (WDM), adding or removing channels leads to increased noise in quantum channels due to classical channel signals, causing error rates to exceed thresholds, requiring manual adjustments of optical attenuators and amplifiers, which is time-consuming and disruptive to network operations.
Innovation Solution
An active channel attenuation/amplification device that automatically adjusts variable optical attenuators and amplifiers based on computed Quantum Bit Error Rate (QBER) and classical channel status, ensuring noise remains below thresholds and optical power is within optimal ranges, allowing continuous key exchange and data transmission without interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If channels are added or removed in a WDM-based QKD system, then network flexibility and adaptability are improved, but noise in quantum channels increases due to classical channel signals, causing error rates to exceed thresholds
Solution Approach 1:
The patent implements a feedback control system where the controller continuously monitors the Quantum Bit Error Rate (QBER) and receives status information from classical channels. When channel additions or removals cause noise to increase and QBER to exceed thresholds, the controller automatically adjusts the optical attenuator to reduce classical signal power or activates/deactivates amplifiers to compensate, thereby maintaining QKD reliability while allowing network reconfiguration
Solution Approach 2:
The system dynamically changes operational parameters including optical attenuation levels and amplifier gain settings in response to channel configuration changes. By adjusting these parameters automatically based on real-time QBER monitoring, the system maintains optimal quantum channel performance despite variations in network topology and channel composition
2Reliability
If manual adjustments of optical attenuators and amplifiers are performed to manage noise, then quantum channel quality is maintained, but network operation is disrupted and time is lost
Solution Approach 1:
The system implements self-service automation where the controller autonomously monitors QBER, detects when noise levels exceed thresholds due to channel changes, and automatically adjusts optical attenuators and amplifiers without human intervention. This eliminates manual adjustments and their associated disruptions, allowing continuous network operation while maintaining quantum channel quality
Solution Approach 2:
The real-time feedback loop continuously monitors quantum channel quality metrics and automatically triggers parameter adjustments when thresholds are exceeded, replacing manual intervention with automated control that maintains reliability without disrupting network productivity
3Productivity
If classical channel signals are transmitted at high power, then data transmission efficiency is improved, but noise in quantum channels increases due to Raman scattering and cross-talk
Solution Approach 1:
The system dynamically adjusts the optical attenuation of classical channels based on real-time QBER monitoring and channel configuration status. When quantum channel quality degrades, the controller automatically reduces classical signal power; when quality is good, classical transmission operates at high efficiency. This dynamic adaptation resolves the contradiction between data transmission efficiency and quantum channel noise
Solution Approach 2:
The optical power parameter of classical channels is changed dynamically based on system state. The controller adjusts attenuation levels to optimize the balance between classical data transmission efficiency and quantum channel noise levels, allowing both functions to operate at optimal performance points under different conditions
Data Source
AI summary
The invention relates to a QKD System Active combiner (200) adapted to be installed in a QKD apparatus, said QKD apparatus comprising an emitter (100), a receiver (110) and QKD systems (102/112), wherein the emitter (100) is adapted to send communication signals to the receiver (110) through the QKD System Active combiner (200), characterized in that the QKD System Active combiner (200) comprises an active attenuation system comprising a processing unit (230) adapted to automatically control at least one variable optical attenuator (150) through a control channel (290) in order to control an attenuation of a signal to be sent to the receiver, and a detector/monitor (240) adapted to monitor the intensity of the signal downstream the attenuation, and wherein the processing unit is adapted to control the variable optical attenuator (150) based on a QBER information or an intensity of a signal received by the receiver, sent by the QKD systems (112) through a classical channel (250).