arXiv subjects

Xiao-Ran Sun

Publications and source records attributed to Xiao-Ran Sun.

4 recordsLinked to original sources

arXiv2026

Scalable and Highly Fault-Tolerant Circular Quantum Byzantine Agreement

Quantum Byzantine agreement (QBA), a cornerstone of quantum blockchain, offers inherent advantages in security and fault tolerance over classical protocols, guaranteed by the laws of quantum mechanics. However, existing multiparty QBA protocols face challenges for large-scale deployment due to exponential communication complexity or reliance on complex multi-particle entanglement. To address this, we propose a multiparty circular QBA protocol that adopts a semi-decentralized architecture, leveraging circular message gathering and quantum digital signatures to achieve quadratic communication complexity and enhanced fault tolerance. Our protocol is experimentally feasible, requiring only weak coherent states, and is compatible with existing star-shaped quantum networks. Simulations conducted on a global satellite-to-ground network demonstrate that the protocol sustains high consensus rates among multiple users, even when employing different key generation protocols under realistic conditions. This work presents a scalable framework for large-scale QBA networks, establishing the foundation for a practical quantum blockchain that enables secure and fault-tolerant decentralized services.

quant-ph↗

arXiv2026

Experimental Coherent One-Way Quantum Key Distribution with Simplicity and Practical Security

Coherent one-way quantum key distribution (COW-QKD) has been widely investigated, and even been deployed in real-world quantum network. However, the proposal of the zero-error attack has critically undermined its security guarantees, and existing experimental implementations have not yet established security against coherent attacks. In this work, we propose and experimentally demonstrate an information-theoretically secure COW-QKD protocol that can resist source side-channel attacks, with secure transmission distances up to 100 km. Our system achieves a secure key rate on the order of kilobits per second over 50 km in the finite-size regime, sufficient for real-time secure voice communication across metropolitan networks. Furthermore, we demonstrate the encrypted transmission of a logo with information-theoretic security over 100 km of optical fiber. These results confirm that COW-QKD can simultaneously provide simplicity and security, establishing it as a strong candidate for deployment in small-scale quantum networks.

quant-ph↗

arXiv2025

Experimentally validated quantum-secure federated learning over a multi-user quantum network

Federated learning enables decentralized, privacy-preserving training but remains vulnerable to privacy leakage in the quantum era. Quantum federated learning (QFL) offers a promising path towards enhanced security and efficiency. However, a practical and experimentally validated QFL protocol utilizing near-term quantum techniques to address data privacy has been lacking. Here we present QuNetQFL, a QFL protocol implemented on quantum networks, in which local model updates are masked with distributed quantum secret keys, offering information-theoretic security during aggregation. We experimentally validate the protocol on a four-client quantum network and benchmark its performance using the generated keys on quantum and real-world datasets. Adding a single quantum client significantly improves global accuracy for classifying multipartite entangled and non-stabilizer quantum datasets. For language tasks, we apply QuNetQFL to sentiment analysis by federated fine-tuning of a hybrid classical-quantum language model, achieving comparable and robust performance in simulation and on real quantum hardware. Large-scale simulations further demonstrate scalability to 200 clients for handwritten-digit recognition, with rapid convergence and a $75\%$ reduction in communication cost via model compression. Our work establishes a practical and scalable route to quantum-secure federated learning for the emerging quantum internet.

quant-ph↗

arXiv2024

Experimental coherent-state quantum secret sharing with finite pulses

Quantum secret sharing (QSS) plays a significant role in multiparty quantum communication and is a crucial component of future quantum multiparty computing networks. Therefore, it is highly valuable to develop a QSS protocol that offers both information-theoretic security and validation in real optical systems under a finite-key regime. In this work, we propose a three-user QSS protocol based on phase-encoding technology. By adopting symmetric procedures for the two players, our protocol resolves the security loopholes introduced by asymmetric basis choice without prior knowledge of the identity of the malicious player. Kato's concentration inequality is exploited to provide security against coherent attacks with the finite-key effect. Moreover, the practicality of our protocol has been validated under a 30-dB channel loss with a transmission distance of 5-km fiber. Our protocol achieves secure key rates ranging from 432 to 192 bps by choosing different pulse intensities and basis selection probabilities. Offering enhanced security and practicality, our protocol stands as an essential element for the realization of quantum multiparty computing networks.

quant-ph↗