Rong 等人於 2021 年 Quantum Information Processing 發表了一 篇 Mediated Semi-Quantum Secure Direct Communication，此篇協定提 出了兩方皆為傳統使用者的中介半量子安全直接通訊協定，透過第三 方量子使用者的協助，優化 Quantum Secure Direct Communication 兩 方皆為量子使用者的設計，並且也優化 Semi-quantum Secure Direct Communication，一方為量子使用者另一方為傳統使用者的設計，在研 究此篇協定時，發現傳統使用者須具備產生量子位元的能力以及透過 量子通道回傳產出的量子給第三方量子使用者，與想像中的傳統使用 者來的高出許多能力，於是進行了此篇協定的研究。在本次研究中， 本研究提出了 Lightweight Mediated Semi-Quantum Secure Direct Communication (LMSQSDC) 的協定，利用圖態所擁有的特性，設計出 第三方使用者僅需進行一次性的分發及量測，改善 MSQSDC 安全性 問題，並且降低傳統使用者所需具備的能力，並且進行量子效能分析， 透過本研究所提出的協定，可以大幅提升 MSQSDC 的量子效率。

Rong et al. published a paper titled "Mediated Semi-Quantum Secure Direct Communication" in Quantum Information Processing in 2021. This protocol proposes a mediated semi-quantum secure direct communication scheme where both parties are classical users, optimized with the assistance of a third-party quantum user, enhancing the design of Quantum Secure Direct Communication (QSDC) for two quantum users and also optimizing Semi-quantum Secure Direct Communication (SQSDC) for one quantum user and one classical user. During the research for this protocol, it was found that classical users need to possess the ability to generate quantum bits and transmit the produced quantum bits back to the third-party quantum user via a quantum channel, requiring much more capability than initially anticipated for classical users. Consequently, the study of this protocol was initiated.
This research proposes the Lightweight Mediated Semi-Quantum Secure Direct Communication (LMSQSDC) protocol. By leveraging the properties inherent in graph states and designing a scheme where the third- party user only needs to perform one-way distribution and measurement, this protocol addresses security issues in MSQSDC and reduces the capabilities required for classical users. Additionally, quantum efficiency analysis is conducted. The protocol proposed in this study significantly enhances the quantum efficiency of MSQSDC.

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