Quantum Communication Leap
In a groundbreaking development for quantum communication, a team of researchers, spearheaded by luminaries like Jianwei Pan and Qiang Zhang from the University
of Science and Technology of China (USTC), part of the Chinese Academy of Sciences (CAS), has successfully demonstrated a pivotal component for scalable quantum repeaters. This innovation allowed them to conduct device-independent quantum key distribution (DI-QKD) over an impressive distance of 100 kilometers. This achievement, detailed in prestigious journals like Nature and Science, represents a significant stride towards realizing a fully functional quantum internet. It also underscores China's leading role in the rapidly evolving field of quantum research and technology, pushing the boundaries of what's possible in secure and efficient information exchange.
The Entanglement Challenge
At the core of quantum information science lies the ambition to construct networks that are both exceptionally secure and remarkably efficient. These advanced quantum networks aim to integrate quantum metrology for precise measurements, quantum communication for unhackable data transfer, and distributed quantum computing for unparalleled processing power. However, a formidable hurdle has been the reliable distribution of quantum entanglement across vast distances. Entanglement, a peculiar quantum phenomenon, is indispensable for building extensive quantum networks. The challenge arises because photons, the carriers of quantum information, experience losses as they travel through optical fibers. This attenuation severely limits the direct transmission range of entanglement, consequently constraining the reach of quantum key distribution, a fundamental technique for secure communication. Previous DI-QKD experiments, which offer robust security even when the involved devices are not entirely trustworthy, were confined to mere hundreds of meters.
Pioneering Repeater Technology
To overcome the distance limitations, the research group engineered a novel quantum repeater system. This system is designed to establish entanglement between two distinct nodes by utilizing quantum memory. The breakthrough lies in their ability to create long-lived entanglement suitable for the architectures of scalable quantum repeaters. By strategically employing entanglement swapping between these entangled nodes, the scientists were able to extend the reach of quantum entanglement significantly further than previously possible. This marks a world-first achievement in generating quantum entanglement that persists long enough to facilitate inter-segment connections, a crucial step for practical long-distance quantum networks. The sustained entanglement quality is paramount, allowing for the subsequent high-fidelity operations required for quantum communication protocols over extended ranges.
Extending Secure Communication
Building upon their advancements in quantum repeater technology, the researchers successfully extended the operational distance of device-independent quantum key distribution (DI-QKD) to over 100 kilometers. This accomplishment is a critical leap forward, simultaneously demonstrating long-distance, high-fidelity atom-to-atom entanglement, which is the bedrock of scalable quantum repeaters. Professor Jiawei Pan, a key figure in the research and executive vice president of USTC, emphasized the pivotal role of quantum repeaters, referring to them as the essential 'building blocks' for connecting future universal quantum computers, which are projected to emerge within the next decade. This development signifies the imminent realization of the quantum internet, capable of linking sophisticated information sensing devices and supercomputing resources with unparalleled security and efficiency.
