Quantum key distribution with multiphoton pulses: An advantage

TL;DR

This paper proposes a quantum key distribution protocol using coincidence measurements that enhances secure key rates over longer distances, outperforming traditional BB84 implementations.

Contribution

It introduces a novel protocol based on coincidence measurements and demonstrates its practical advantage through experimental implementation.

Findings

Achieved around 74% more key bits per pulse compared to GLLP analysis of BB84.

Demonstrated higher secure key rate over longer distances.

Validated the protocol with a proof-of-concept experiment.

Abstract

In this article, we introduce a quantum key distribution protocol for the line of sight channels based on coincidence measurements. We present a proof-of-concept implementation of our protocol. We show that using coincidence measurements to monitor multi-photon pulses results in a higher secure key rate over longer distances for such channels. This key rate is higher than popular implementations of quantum key distribution protocol based on BB84, for example, the GLLP analysis [Quant. Info. Comput. \textbf{4}, 325 (2004)]. In the experiment, we could generate around $74 \%$ more key bits per signal pulse as compared to the GLLP analysis of BB84 protocol with similar parameters and equal value of mean photon number.