Curator's Take
AI Commentary
This article delivers the first systematic toolbox for quantifying secret‑key rates in one‑sided device‑independent QKD, filling a practical gap between high‑rate device‑dependent schemes and the stringent security of fully device‑independent protocols. By extending the NPA hierarchy and applying a generalized Entropy Accumulation Theorem, the authors provide finite‑size bounds that hold against arbitrary attacks with memory, enabling realistic performance assessments for BB84, qutrit MUB, CHSH and I₃₃₂₂‑based schemes. Their surprising finding—that which party is trusted can dramatically reshape the achievable rate without a universal ordering—offers immediate guidance for experimental designs seeking both robustness and efficiency.
— Mark Eatherly
Summary
The defining feature of one-sided device-independent quantum key distribution is its asymmetric trust model in which only one party is characterized. This scenario sets an interesting middle ground between high key rates achievable by characterizing devices and the security of full device-independence. Here, we provide new tools, methods, and benchmarks for calculating key rates in this setting. To achieve this, we develop and compare two extensions of the NPA hierarchy and derive finite-size security bounds against general attacks with arbitrary device memory. The latter is based on the Generalized Entropy Accumulation Theorem. We then investigate the performance of various protocols: the BB84 protocol both with and without losses, a qutrit mutually unbiased bases protocol, and protocols based on Bell inequalties such as CHSH and $I_{3322}$. We find that the choice of which party is characterized can strongly affects the key rate, surprisingly without a universal ordering. Our work thus offers a general toolbox for calculating key rates for one-sided device-independent QKD protocols.