Optimization of Information Reconciliation for Decoy-State Quantum Key Distribution over a Satellite Downlink Channel

2025-11-07

AI Summary

To address the short pass duration and low key generation rate (KGR) of satellite-to-ground decoy-state quantum key distribution (QKD) in low Earth orbit (LEO), this paper proposes a dynamic downlink-oriented information reconciliation optimization method. We innovatively integrate time-varying geometric configurations throughout the satellite pass, atmospheric scintillation effects, and decoy-state optical intensity attenuation to establish a high-accuracy dynamic quantum bit error rate (QBER) model. Based on this model, we design a prior-driven adaptive information reconciliation algorithm, enabling efficient key error correction within the BB84 decoy-state protocol framework. Experimental evaluation under realistic satellite-to-ground channel conditions demonstrates a 2.9% increase in secure key length, significantly enhancing system practicality and key generation efficiency.

Technology Category

• Search and Optimization: Distributed Search
• Intelligent Robots: State Estimation
• Machine Learning: Quantum Machine Learning

Application Category

• Security and Privacy: Large-scale security measurements
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

Abstract

Quantum key distribution (QKD) is a cryptographic solution that leverages the properties of quantum mechanics to be resistant and secure even against an attacker with unlimited computational power. Satellite-based links are important in QKD because they can reach distances that the best fiber systems cannot. However, links between satellites in low Earth orbit (LEO) and ground stations have a duration of only a few minutes, resulting in the generation of a small amount of secure keys. In this context, we investigate the optimization of the information reconciliation step of the QKD post-processing in order to generate as much secure key as possible. As a first step, we build an accurate model of the downlink signal and quantum bit error rate (QBER) during a complete satellite pass, which are time-varying due to three effects: (i) the varying link geometry over time, (ii) the scintillation effect, and (iii) the different signal intensities adopted in the Decoy-State protocol. Leveraging the a-priori information on the instantaneous QBER, we improve the efficiency of information reconciliation (IR) (i.e., the error correction phase) in the Decoy-State BB84 protocol, resulting in a secure key that is almost 3% longer for realistic scenarios.

Problem

• Optimizing information reconciliation in satellite quantum key distribution systems
• Addressing time-varying quantum bit error rates in satellite downlink channels
• Improving secure key generation efficiency for short-duration satellite passes

Innovation

• Modeled time-varying satellite downlink signal and QBER
• Improved information reconciliation efficiency using QBER knowledge
• Increased secure key length by nearly 3%