Quantum Key Generation with Split Optical Signal Validation
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Solution Overview
Problem
In quantum key distribution systems, especially in continuous-variable quantum key distribution (CV-QKD), the modulation process in the modulator often results in inaccurate key transmission due to inherent component disadvantages, leading to a weak association between the initial key and the key carried by the modulated optical signal, which decreases the success rate of key preparation and transmission, causing resource waste.
Innovation Solution
A key generation device comprising a key generator, modulator, light source generator, beam splitter, attenuator, and data obtainer, where the modulated optical signal is split to obtain sub signals, and the attenuator reduces photon quantity to an extremely weak coherent state, ensuring a strong association between the initial and transmitted keys, thereby improving transmission success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the modulator modulates the light source using the initial key, then the key transmission process is completed, but the association between the initial key and the key carried by the modulated optical signal becomes weak due to inherent component disadvantages
Solution Approach 1:
The patent implements a feedback mechanism where the modulated optical signal is detected and the detected key is fed back to compare with the initial key. Based on this feedback, the system determines whether to discard and re-prepare keys or to use them for communication, thereby improving the reliability of key association while maintaining productivity through intelligent decision-making
Solution Approach 2:
The system performs self-validation by detecting the modulated signal and comparing the detected key with the initial key. This self-service mechanism allows the system to automatically identify failed key transmissions and trigger re-preparation only when necessary, resolving the contradiction between reliability and productivity
2Reliability
If the transmit-end device and receive-end device detect high bit error rate, then key security is ensured, but system resources are wasted due to repeated key preparation failures
Solution Approach 1:
The patent performs preliminary detection of the modulated optical signal at the transmit-end device before actual transmission. By detecting the signal and verifying key association in advance, the system can identify failed preparations early and avoid wasting resources on transmitting incorrect keys, thus maintaining security while reducing resource loss
Solution Approach 2:
The system quickly discards and re-preparers keys that fail the association check, rather than attempting to correct or reuse them. This skipping approach prevents resource waste on fundamentally flawed keys while maintaining security through rapid iteration and verification
Data Source
AI summary
A key generation method includes modulating a first key to a first light source signal, to obtain a modulated optical signal, splitting the modulated optical signal, to obtain a first sub modulated optical signal and a second sub modulated optical signal, attenuating the first sub modulated optical signal such that a quantity of photons included in each period of the first sub modulated optical signal is less than a preset value, and sending an attenuated first sub modulated optical signal to a receive-end device, and obtaining a second key carried in the second sub modulated optical signal, and storing the second key.