Security of quantum key distribution with source and detector imperfections through phase-error estimation

Abstract: Quantum key distribution (QKD) promises information-theoretic security based on quantum mechanics, but practical implementations face security vulnerabilities due to device imperfections. Recent advances have separately addressed source and detector imperfections in phase-error-estimation based security proof frameworks, but this is not enough to protect real-world QKD systems suffering from both types of imperfections simultaneously. In this work, we show that existing techniques for BB84-type protocols can be combined to construct a unified security proof that simultaneously accounts for both source and detector imperfections. Our approach thus represents a significant step towards closing the gap between theoretical security proofs and practical QKD implementations.