Feasibility of entanglement-based QKD protocols with SPDC and QD sources

TL;DR

This paper evaluates the practicality of entanglement-based QKD using SPDC and QD sources, considering real-world imperfections like multiphoton emissions, FSS, and detector inefficiencies, to guide future secure quantum communication implementations.

Contribution

It provides a comprehensive theoretical analysis of the limitations of SPDC and QD sources for entanglement-based QKD under realistic conditions.

Findings

SPDC sources are unsuitable for secure DI-QKD due to multiphoton emissions.

FSS in QD sources reduces protocol performance.

Imperfect detection significantly impacts the feasibility of practical QKD.

Abstract

We theoretically analyze the feasibility of entanglement-based quantum key distribution (QKD) protocols considering widely used spontaneous parametric down-conversion (SPDC) and novel quantum dot (QD) sources. We account for multiphoton emission in SPDC sources and fine-structure splitting (FSS) in QD. In addition, we incorporate imperfect detection, including dark counts and limited efficiency. For SPDC sources, we confirm that the presence of vacuum and multiphoton pairs renders them unsuitable for secure device-independent (DI) QKD implementations under standard detection strategies. Conversely, in the case of QD sources, accounting for the effects of FSS, results in reduced performance of protocols. Our findings are crucial for the practical implementation of entanglement-based QKD protocols using realistic sources and detectors.