Security of quantum key distribution with arbitrary individual imperfections

TL;DR

This paper analyzes the security of the BB84 quantum key distribution protocol considering arbitrary imperfections in sources and detectors, providing a secure key rate based on just two bounded parameters.

Contribution

It introduces a security proof that requires only bounding the source basis dependence and detector blinding parameter, even with uncharacterized systems and high losses.

Findings

Security can be maintained with arbitrary source and detector imperfections.

Only two parameters need to be bounded for security assurance.

The protocol remains secure despite large system losses.

Abstract

We consider the security of the Bennett-Brassard 1984 (BB84) protocol for Quantum Key Distribution (QKD), with arbitrary individual imperfections simultaneously in the source and detectors. We provide the secure key generation rate, and show that only two parameters must be bounded to ensure security; the basis dependence of the source and a detector blinding parameter. The system may otherwise be completely uncharacterized and contain large losses.