Device-independent quantum key distribution secure against adversaries with no long-term quantum memory

TL;DR

This paper presents a more efficient and noise-resistant security proof for device-independent quantum key distribution that applies to arbitrary Bell inequalities, assuming adversaries lack long-term quantum memory.

Contribution

It introduces a general security proof for DIQKD that is more practical and adaptable, assuming adversaries do not possess long-term quantum memory.

Findings

Enhanced noise tolerance in DIQKD security proofs

Applicability to protocols based on any Bell inequality

Security against supra-quantum no-signalling adversaries

Abstract

Device-Independent Quantum Key Distribution (DIQKD) is a formalism that supersedes traditional quantum key distribution, as its security does not rely on any detailed modelling of the internal working of the devices. This strong form of security is possible only using devices producing correlations that violate a Bell inequality. Full security proofs of DIQKD have been recently reported, but they tolerate zero or small amounts of noise and are restricted to protocols based on specific Bell inequalities. Here, we provide a security proof of DIQKD that is both more efficient and noise resistant, and also more general as it applies to protocols based on arbitrary Bell inequalities and can be adapted to cover supra-quantum eavesdroppers limited by the no-signalling principle only. It requires, however, the extra assumption that the adversary does not have a long-term quantum memory, a condition that is not a limitation at present since the best existing quantum memories have very short coherence times.