Security analysis of mode-pairing quantum key distribution with flexible pairing strategy

Area of Science:

• Quantum Information Science
• Secure Communication Technologies
• Cryptography

Background:

• Mode-pairing quantum key distribution (MP-QKD) offers advantages for long-distance secure communication due to its simple implementation and quadratic scaling capacity.
• Post-measurement pairing in MP-QKD reduces photon-coincidence demands, crucial for exceeding fundamental key-rate transmission limits.

Purpose of the Study:

• To propose an enhanced decoy-state MP-QKD protocol with a flexible and efficient pairing strategy.
• To prove the security of the proposed scheme using an entanglement model.
• To demonstrate the improvement in secret key rate (SKR) and achievable distance.

Main Methods:

• Development of an improved decoy-state MP-QKD protocol.
• Security proof based on an entanglement model for decoy-state MP-QKD.
• Simulations to evaluate SKR and achievable distance.

Main Results:

• The proposed MP-QKD protocol significantly enhances SKR across all distances compared to the original scheme.
• SKR improvements exceed 65% within 375 km (asymptotic) and 50% within 400 km (finite case).
• Achievable distance is extended, particularly in the finite case with small block lengths.

Conclusions:

• The enhanced decoy-state MP-QKD protocol demonstrates high efficiency and promotes practical applicability.
• The developed entanglement model provides a theoretical foundation for future analyses of decoy-state MP-QKD.
• The protocol offers substantial improvements in key rate and distance for secure communication.