Quantum Key Generation with Split Optical Signal Verification
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Solution Overview
Problem
In quantum key distribution systems, the inherent disadvantages of modulators lead to inaccurate modulation of keys, resulting in a weak association between the key stored at the transmit-end device and the key received at the receive-end device, which decreases the success rate of key preparation and transmission, causing system resource waste.
Innovation Solution
A key generation device that includes a modulator, a light source generator, a beam splitter, and an attenuator, where the modulated optical signal is split to obtain two sub signals, with the attenuated sub signal sent to the receive-end device, and the second sub signal used to obtain a key that is stored and used for communication, ensuring a strong association between the keys at both ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the modulator modulates the light source using a random key, then the key can be transmitted through the quantum channel, but the inherent disadvantages of the modulator cause inaccurate modulation, resulting in a weak association between the transmitted key and the received key
Solution Approach 1:
The patent implements a feedback mechanism where the transmit-end device detects the modulated optical signal and obtains a detected key, then compares it with the original random key to calculate an association degree. When the association degree is below a threshold, the system performs feedback adjustment by modifying the modulation process or key selection, ensuring the association strength meets requirements before transmission.
Solution Approach 2:
The patent performs preliminary detection and association verification at the transmit-end device before the key transmission is considered complete. The system detects the modulated signal, obtains the detected key, calculates the association degree with the original key, and only proceeds with transmission when the association meets the threshold, preventing weak-association keys from being transmitted.
2Reliability
If the transmit-end device and receive-end device discard mismatched keys and re-prepare new keys, then key security is maintained, but the success rate of key preparation decreases and system resources are wasted
Solution Approach 1:
The patent performs preliminary association verification at the transmit-end device before transmission by detecting the modulated signal and comparing the detected key with the original key. This preliminary check ensures that only keys with strong association are transmitted, eliminating the need for discard-and-reprepare cycles at the receive-end device and improving preparation success rate.
Solution Approach 2:
The system implements feedback control where the transmit-end device monitors the association degree between original and detected keys. When the association degree meets the threshold, the system confirms successful key preparation and proceeds with transmission. This feedback mechanism prevents unnecessary discarding of valid keys and reduces resource waste from repeated key generation.
Data Source
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AI summary
This application relates to a key generation device and method, and belongs to the field of quantum communications technologies. The 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, so 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, where the second key is a key obtained after a bit error occurs when the first key is modulated to the first light source signal, and the second key is a key to be used during communication with the receive-end device. According to the key generation method provided in embodiments of this application, a success rate of preparing and transmitting a key can be improved, thereby avoiding system resource waste.