Reliability-driven framework for multidimensional reconciliation in CV-QKD

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Optical Communication Systems

Background:

• Continuous-variable quantum key distribution (CV-QKD) systems face performance limitations due to unreliable Gaussian-modulated coherent states (GMCSs) in multidimensional reconciliation (MR).
• Conventional MR schemes struggle with intra-vector reliability and inter-vector imbalance, hindering secure key distribution over longer distances.

Purpose of the Study:

• To propose and evaluate a novel reliability-driven preprocessing framework for MR in CV-QKD systems.
• To enhance the robustness and efficiency of CV-QKD by addressing the unreliability of GMCSs.
• To extend the secure transmission distance of CV-QKD systems through improved reconciliation protocols.

Main Methods:

• Development of a multi-step sample interleaver to enhance intra-vector reliability and reduce inter-vector imbalance of GMCSs.
• Introduction of a bit-allocation strategy to match the reliability of MR soft information with forward error correction (FEC) code requirements.
• Investigation of simplified log-likelihood ratio (LLR) estimation methods to reduce implementation overhead.

Main Results:

• The proposed reliability-driven framework significantly improves frame error rate (FER) performance compared to conventional MR schemes.
• The framework achieves these improvements with only negligible additional latency.
• Enhanced reliability of processed quantum states leads to extended achievable transmission distances for CV-QKD.

Conclusions:

• The proposed reliability-driven preprocessing framework offers a substantial advancement for MR in CV-QKD systems.
• This approach effectively mitigates the impact of unreliable GMCSs, enhancing overall system security and performance.
• The framework enables longer-distance secure key distribution, a critical step for practical CV-QKD deployment.