by Oui
Tue Feb 24th, 2026 at 12:25:10 PM EST
h/t Dutch De Volkskrant newspaper ...
Quantum internet: Chinese physicists build 'the very best you can achieve right now'
Chinese researchers have come one step closer to a future quantum internet, a futuristic network that will allow users to exchange unhackable information, conduct high-frequency trading, and make data centers more efficient. "The first applications are getting closer and closer."
100 kilometers, roughly the distance from Leiden to Den Helder: that is the distance over which Chinese physicists have established and used a stable quantum connection. They recently reported this in the journal Science.
Device-independent quantum key distribution over 100 km with single atoms
Device-independent quantum key distribution (DI-QKD) is a key application of the quantum internet. We report the realization of DI-QKD between two single-atom nodes linked by 100-kilometer (km) fibers. To improve the entangling rate, single-photon interference is leveraged for entanglement heralding, and quantum frequency conversion is used to reduce fiber loss.
A tailored Rydberg-based emission scheme suppresses the photon recoil effect on the atom without introducing noise. We achieved high-fidelity atom-atom entanglement and positive asymptotic key rates for fiber lengths up to 100 km. At 11 km, 1.2 million heralded Bell pairs were prepared over 624 hours, yielding an estimated extractable finite-size secure key rate of 0.112 bits per event against general attacks. Our results close the gap between proof-of-principle quantum network experiments and real-world applications.
A breakthrough in quantum repeater technology has enabled secure quantum communication over 100 kilometers.
Researchers led by Jianwei Pan, Qiang Zhang, and Xiaohui Bao at the University of Science and Technology of China (USTC), part of the Chinese Academy of Sciences (CAS), have achieved a major milestone in quantum communication. For the first time, they demonstrated a key component required for scalable quantum repeaters, which later allowed them to carry out device-independent quantum key distribution (DI-QKD) across 100 kilometers.
The results, published in Nature and in Science, represent important progress toward building a functional quantum internet. The work also reinforces China's position at the forefront of quantum research and technology.
At the heart of quantum information science is the effort to create networks that are both highly secure and highly efficient. These quantum networks would combine quantum precision metrology, quantum communication, and distributed quantum computing. Together, these capabilities could enable extremely sensitive measurements, secure data transmission, and dramatically faster information processing.
Overcoming Distance Limits in Quantum Communication
A major technical challenge has been reliably distributing quantum entanglement over long distances. Entanglement is essential for large-scale quantum networks, but photons traveling through optical fibers are gradually lost, which sharply restricts how far entanglement can be directly transmitted.
This same problem has limited quantum key distribution, a cornerstone of secure quantum communication. While DI-QKD ensures security even if the devices involved cannot be fully trusted, previous experiments were restricted to distances of only a few hundred meters.
To push beyond this boundary, the team developed a quantum repeater system capable of creating memory-memory entanglement between two separate nodes. By linking these nodes through entanglement swapping, the researchers successfully extended entanglement across much greater distances.
