Quantum Key Distribution Device Error Correction QBER
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Solution Overview
Problem
In quantum key distribution systems, the high quantum bit error rate (QBER) associated with decoy and vacuum pulses hinders efficient error correction, leading to reduced cryptographic key generation efficiency due to high error rates and prolonged processing times.
Innovation Solution
A quantum key distribution device that performs error correction on the entire shared bit string, using error position information to calculate QBER for each type of pulse and base, thereby avoiding the inefficiencies of dividing bit strings by pulses and bases, and enabling effective privacy amplification for cryptographic key generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If error correction is performed for each combination of pulse type and base type, then measurement precision of QBER is improved, but productivity of cryptographic key generation deteriorates due to high processing time
Solution Approach 1:
The patent segments the QBER calculation process by separating error detection from error correction. Error detection is performed on the entire shared bit string to identify error positions, while error correction is then applied specifically to those identified error positions rather than processing all bits for each pulse-base combination.
Solution Approach 2:
The patent extracts only the error positions from the shared bit string using error detection, and then applies error correction only to those specific positions. This extraction approach avoids the computational overhead of processing entire bit strings for each pulse-base combination while maintaining accurate QBER measurement.
2Measurement precision
If bit string is divided by pulses and bases for error correction, then measurement precision of error rate is improved, but loss of time increases due to prolonged processing
Solution Approach 1:
The patent performs preliminary error detection on the entire shared bit string before dividing it into pulse-base combinations for error correction. This preliminary action identifies error positions in advance, allowing subsequent error correction to be focused only on affected bits rather than processing all bits across all combinations.
Solution Approach 2:
The error detection mechanism serves the error correction process by automatically identifying error positions that need correction. This self-service approach eliminates the need for separate comprehensive error correction processing of all bit strings, reducing processing time while maintaining measurement precision.
3Reliability
If decoy and vacuum pulses are used to prevent photon number splitting attacks, then reliability of cryptographic key security is improved, but quantum bit error rate increases leading to more errors
Solution Approach 1:
The patent extracts and identifies specific error positions caused by decoy and vacuum pulses using error detection, then applies error correction only to those positions. This approach removes the harmful effect of high QBER in these pulses without discarding the entire bit string, maintaining security while reducing errors.
Solution Approach 2:
The patent converts the high error rate generated by decoy and vacuum pulses into useful information by using error detection to identify error positions. These positions are then corrected using error correction, transforming the harmful high QBER into an opportunity for targeted error remediation that improves overall key reliability.
Data Source
AI summary
According to an embodiment, a quantum key distribution device includes a quantum key distributor, a sifter, a corrector, an identifier, a classifier, a calculator, and a privacy amplifier. The quantum key distributor obtains a photon string from a photon string of two or more intensities of light pulses. The sifter obtains pulse information indicating the light pulse to which each bit of a shared bit string corresponds. The corrector corrects an error included in the shared bit string and generates a post-correction bit string. The identifier generates error position information. The classifier classifies each bit of the post-correction bit string. The calculator calculates the error rate for each light pulse and each base using the error position information. The privacy amplifier generates a cryptographic key from the post-correction bit string on the basis of the error rate.