Zeng-Bing Chen

Quantum conference key agreement facilitates the secure communication among multiple parties through multipartite entanglement, which is anticipated as an important cryptographic primitive for future quantum networks. However, the experimental complexity and low efficiency associated with synchronous detection of multipartite entanglement state have significantly hindered the practical application. Here, we propose a measurement-device-independent conference key agreement protocol utilizing asynchronous Greenberger-Horne-Zeilinger state measurement and achieve a linear scaling of the conference key rate among multiple parties, which has the similar performance with the single-repeater scheme in quantum network. The asynchronous measurement strategy bypasses the necessity for complex global phase-locking technologies, concurrently extending the intercity transmission distance with composable security in finite key regime. Our work also showcases the advantages of the asynchronous pairing concept in multiparty quantum entanglement.

E-commerce, a type of trading that occurs at a high frequency on the Internet, requires guaranteeing the integrity, authentication and non-repudiation of messages through long distance. As current e-commerce schemes are vulnerable to computational attacks, quantum cryptography, ensuring information-theoretic security against adversary's repudiation and forgery, provides a solution to this problem. However, quantum solutions generally have much lower performance compared to classical ones. Besides, when considering imperfect devices, the performance of quantum schemes exhibits a notable decline. Here, we demonstrate the whole e-commerce process of involving the signing of a contract and payment among three parties by proposing a quantum e-commerce scheme, which shows resistance of attacks from imperfect devices. Results show that with a maximum attenuation of 25 dB among participants, our scheme can achieve a signature rate of 0.82 times per second for an agreement size of approximately 0.428 megabit. This proposed scheme presents a promising solution for providing information-theoretic security for e-commerce.