Performance of BB84 without decoy states under varying announcement structures

TL;DR

This paper compares the performance of three quantum key distribution protocols without decoy states under various channel conditions, highlighting their specific advantages and robustness in practical implementations.

Contribution

It provides a numerical security analysis of BB84, SARG04, and NPAB BB84 protocols without decoy states, revealing their relative strengths in different channel scenarios.

Findings

BB84 is robust against errors and depolarization

SARG04 performs well in high loss channels

NPAB BB84 offers advantages against device misalignment

Abstract

In phase-randomized weak coherent pulse (WCP) implementations of Quantum Key Distribution (QKD) BB84 protocol, the decoy method is often used to compensate BB84's vulnerability against photon number splitting (PNS) attacks. However, this typically introduces extra complexities and requirements on experimental devices. In this paper, we are therefore interested in phase-randomized WCP implementations without the decoy method. We examine the performance of three QKD protocols with different classical announcement structures, namely BB84, SARG04, and No Public Announcement of Basis (NPAB) BB84, using numerical security proof techniques. We compare secure key rates of the three protocols in asymptotic and finite-size regimes for lossy and noisy channels. The three protocols show different relative advantages depending on the channel behaviour. Canonical BB84 shows robustness against errors and depolarization, SARG04 demonstrates resilience against high loss channels, and NPAB BB84 shows potential advantages against physical misalignment between QKD devices.