A research team at PolyU has reached a major milestone by developing a quantum communication chip, paving the way for Hong Kong’s first quantum communication network. This advancement showcases PolyU’s proactive efforts to address cybersecurity risks in the quantum era. Additionally, it promotes the commercialisation of quantum communication while aligning with China’s strategic goals for industrial development, as outlined in the Nation’s “15th Five-Year Plan”.

Led by Professor Liu Ai-Qun, Director of the Research Institute for Quantum Technology (RIQT) and Chair Professor of Quantum Engineering and Science of the Department of Electrical and Electronic Engineering, and Hong Kong Global STEM Scholar, the research team successfully conducted a cybersecurity test on the world’s longest optical fibre quantum network, built using this quantum chip platform. They developed a compact quantum chip measuring just 12mm × 4mm, utilising semiconductor fabrication techniques.

With support from HKCOLO.NET, which donated the optical fibre network, the team performed a quantum encrypted transmission test over an existing network approximately 55 kilometres long. This network connected four nodes across Hong Kong, Kowloon, and the New Territories, including PolyU, another university, and two major data centres in Tseung Kwan O and Chai Wan. During the trial, the quantum chip effectively encoded and emitted photons containing quantum information, enabling the secure transmission of encrypted messages across the network.

Operating at a clock rate of 1.25 GHz, the quantum chip generates and transmits high-quality quantum-encoded signals with remarkable stability, supporting secure key generation at a rate of 45.73 kbps. This capability allows reliable encrypted optical fibre communications over distances exceeding 100 kilometres. Furthermore, the system dynamically adjusts to environmental factors such as temperature fluctuations and vibrations, ensuring stable connections and enhancing its potential for commercial deployment.

This new generation of quantum chips is designed for large-scale rollout. Unlike traditional solutions that rely on bulk optical devices, this innovative approach offers four key advantages: high speed, exceptional stability, low cost, and superior scalability for mass production. This compact, lightweight, plug-and-play technology is essential for developing high-performance quantum communication networks. Moreover, its compatibility with existing systems will enable financial institutions and government sectors to transition smoothly while addressing emerging cybersecurity threats.

Professor Liu emphasised, “Our quantum communication encryption is grounded in the principles of quantum mechanics. Since quantum states cannot be cloned, it is theoretically nearly impossible to crack. This small yet powerful quantum chip has the potential to safeguard Hong Kong’s digital financial system and enhance its reputation as an international financial hub, making it a critical asset for our Nation’s economic development.”

Overall, RIQT will continue refining and testing multipoint transmission technology at scale, leading to widespread adoption across various industries while fostering a secure future for Hong Kong’s quantum networks.

The PolyU Quantum Chip offers four major advantages: high speed, high stability, low cost, and superior scalability for mass production.

Prof. Christopher Chao (centre), Senior Vice President (Research and Innovation); Prof. Liu Ai-Qun (left); and Prof. Alan Lau Pak-tao (right), Associate Dean (College of Undergraduate Studies) and Professor at the Department of Electrical and Electronic Engineering, showcasing the PolyU Quantum Chip.