Device-independent quantum key distribution using random quantum states

This article delves into the application of device-independent quantum key distribution (QKD) using random quantum states, offering a comprehensive analysis of their performance and security. The study focuses on entanglement-based QKD protocols, which rely on the no-cloning principle and monogamy relations for security. The authors investigate the impact of device imperfections and implementation loopholes on QKD, emphasizing the advantages of device-independent QKD in mitigating these issues. The primary focus is on the performance of two-qubit mixed states of different ranks in QKD tasks, quantifying their entanglement and Bell-nonlocality. The research reveals that the efficacy of QKD in terms of secure key rates decreases with the increase in the rank of the random state. Notably, the study demonstrates that mixed states with the same magnitude of entanglement can yield different secure key rates, with pure states providing the upper bound and Werner states the lower bound. The findings offer valuable insights into the resilience of random states against quantum attacks and pave the way for further research into their application in various quantum information protocols.