As one of the most disruptive technologies of the 21st century, quantum technology is revolutionising the global technological landscape. The Hong Kong Polytechnic University (PolyU) has achieved a breakthrough by successfully conducting a cybersecurity test on the world's longest optical fibre quantum network, built utilising a quantum chip platform. This milestone marks a stride forward in the commercialisation of quantum communication and aligns with China's strategic priorities, as outlined in the Nation's "15th Five-Year Plan" where it is identified as one of the top technological areas for industry development.
Quantum technology has already unlocked significant value in quantum computers, quantum satellites and precision measurement, and is poised to catalyse classical computing and cryptography. Theoretically, quantum computers, once powerful enough, can instantaneously break current encryption technologies, posing existential security threats to financial transactions, cross-border data privacy, Internet of Things (IoT) device communications, and in other critical areas. In response, countries worldwide are developing post-quantum cryptography or quantum encryption solutions to mitigate the impending cybersecurity risks of the quantum era.
Led by Prof. Ai-Qun LIU, Director of the Research Institute for Quantum Technology (RIQT), Chair Professor of Quantum Engineering and Science of the Department of Electrical and Electronic Engineering, and Hong Kong Global STEM Scholar, a PolyU research team has successfully developed a quantum communication chip to establish Hong Kong's first quantum communication network. Prof. Liu said, "Our quantum communication encryption is grounded in the principles of quantum mechanics: since quantum states cannot be cloned, it is theoretically almost impossible to crack. This small yet mighty quantum chip has the potential to safeguard Hong Kong's digital financial system and its reputation as an international financial hub, making it a critical asset for our Nation's economic development. The PolyU RIQT proudly leads the charge in embracing this crucial mission, harnessing cutting-edge quantum solutions to protect our future."
Under the leadership of Prof. Liu, the team at RIQT has developed a compact quantum chip, measuring just 12mm × 4mm, utilising semiconductor fabrication techniques. The optical fibre network provided by the HKCOLO.NET data centre as a donation enabled the team to complete a quantum encrypted transmission test on an existing optical fibre link spanning approximately 55 kilometres, connecting four nodes across Hong Kong, Kowloon and the New Territories, and including PolyU, another university and two large data centres in Tseung Kwan O and Chai Wan. During the trial, the quantum chip successfully encoded and emitted photons with quantum information, transmitting encrypted messages between points through the network.
The PolyU research team has successfully completed a test on an optical fibre network of approximately 55 kilometres, connecting four nodes across Hong Kong, Kowloon, and the New Territories.
The quantum chip operates at a clock rate of 1.25 GHz, generating and transmitting high-quality quantum-encoded signals with remarkable stability. This enables secure key generation at a rate of 45.73 kbps, facilitating reliable encrypted optical fibre communications over distances exceeding 100 kilometres. Moreover, the system dynamically adapts to environmental factors such as temperature fluctuations and vibrations, maintaining stable connections and paving the way for commercial deployment.
Prof. Christopher CHAO, Senior Vice President (Research and Innovation) of PolyU, commented, "The rapid progress of quantum technology has prompted financial centres worldwide to proactively explore solutions to mitigate cybersecurity risks in the quantum era. As Asia's leading international financial centre, Hong Kong must anticipate the threat posed by quantum computing and prepare ahead of time. This milestone not only addresses a strategic priority of the 15th Five-Year Plan but also aligns with the key initiative of Hong Kong's Innovation and Technology Development Blueprint, which prioritises advanced manufacturing and microelectronics. This quantum chip presents an excellent opportunity for our innovative ecosystem to leverage its capabilities. As a leading research university, PolyU will continue to translate research outcomes into impactful applications, driving Hong Kong's development as a global innovation and technology hub."
Prof. Liu emphasised, "PolyU has pioneered a new generation of quantum chips suitable for massive rollout. Unlike solutions assembled with discrete and bulk optical devices, our innovative approach offers four major advantages: high speed, high stability, low cost and superior scalability for mass production. This compact, lightweight, plug-and-play equipment is essential for building high performance and scalable quantum communication networks. In addition, its compatibility with existing network systems will enable financial institutions and government sectors to smoothly transition their systems, responding to emerging cybersecurity threats amplified by advancements in computing power."
Prof. Ai-Qun Liu (centre) with his research team at the PolyU Research Institute for Quantum Technology.
He reiterated that RIQT will continue to refine and test the multipoint transmission technology at scale, leveraging existing network infrastructure. This will pave the way for the widespread adoption of quantum communication across various scenarios, encompassing multiple industries. Ultimately, Hong Kong can seamlessly transition to the next generation of smart quantum networks, supported by a comprehensive and secure environment.
