A global estimation of the lower bound of the privacy amplification term for decoy-state quantum key distribution

TL;DR

This paper introduces a novel global estimation method for the lower bound of the privacy amplification term in decoy-state quantum key distribution, improving the secure key rate by considering the correlation between yield and error rate.

Contribution

It presents the first comprehensive approach to estimate the privacy amplification lower bound as a whole, enhancing the accuracy of key rate calculations in quantum cryptography.

Findings

Global estimation significantly improves quantum key distribution performance.

The method applies to both BB84 and measurement-device-independent protocols.

Numerical simulations confirm the effectiveness of the new estimation approach.

Abstract

The privacy amplification term, of which the lower bound needs to be estimated with the decoy-state method, plays a positive role in the secure key rate formula for decoy-state quantum key distribution. In previous work, the yield and the bit error rate of single-photon state are estimated separately to gain this lower bound. In this work, we for the first time take the privacy amplification term as a whole to consider this lower bound. The mathematical description for the correlation between the yield and the bit error rate of single-photon state is given with just two unknown variables. Based on this, we obtain the global estimation of this lower bound for both BB84 protocol and measurement-device-independent protocol. The results of numerical simulation show that the global estimation can significantly improve the performance of quantum key distribution.