arXiv subjects

Mengya Zhu

Publications and source records attributed to Mengya Zhu.

3 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↗

arXiv2025

Information-theoretically secure quantum timestamping with one-time universal hashing

Accurate and tamper-resistant timestamps are essential for applications demanding verifiable chronological ordering, such as legal documentation and digital intellectual property protection. Classical timestamp protocols rely on computational assumptions for security, rendering them vulnerable to quantum attacks, which is a critical limitation given the rapid progress in quantum computing. To address this, we propose an information-theoretically secure quantum timestamping protocol based on one-time universal hashing with quantum keys. Our protocol simultaneously achieves information-theoretic security and high efficiency, enabling secure timestamping for arbitrarily long documents. Simulations demonstrate a generation rate exceeding 100 timestamps per second over intercity distances. In addition, our protocol only requires weak coherent states, making it practical for large-scale deployment. This work advances the field of quantum timestamping and contributes to the broader development of quantum cryptography and the future quantum internet.

quant-ph↗

arXiv2016

Efficient Thermal Conductance in Organometallic Perovskite CH3NH3PbI3 Films

Perovskite-based optoelectronic devices have shown great promise for solar conversion and other optoelectronic applications, but their long-term performance instability is regarded as a major obstacle to their widespread deployment. Previous works have shown that the ultralow thermal conductivity and inefficient heat spreading might put an intrinsic limit on the lifetime of perovskite devices. Here, we report the observation of a remarkably efficient thermal conductance, with conductivity of 11.2 +/- 0.8 W m^-1 K^-1 at room temperature, in densely-packed perovskite CH3NH3PbI3 films, via noncontact time-domain thermal reflectance measurements. The temperature-dependent experiments suggest the important roles of organic cations and structural phase transitions, which are further confirmed by temperature-dependent Raman spectra. The thermal conductivity at room temperature observed here is over one order of magnitude larger than that in the early report, suggesting that perovskite device performance will not be limited by thermal stability.

cond-mat.mtrl-sci↗