Researchers have successfully deployed quantum dots, often called ‘artificial atoms’, in a groundbreaking quantum communication experiment between two German cities. This achievement, detailed in a new study published in Light Science & Applications, marks a significant step towards building a secure quantum internet resistant to future cyber threats.
The experiment, conducted by a team of scientists from Leibniz University of Hannover, Physikalisch-Technische Bundesanstalt, and the University of Stuttgart, utilized a 79-kilometer fiber optic link connecting Hannover and Braunschweig. This setup, dubbed the ‘Niedersachsen Quantum Link’, demonstrates the real-world potential of quantum key distribution (QKD) using semiconductor quantum dots.
Artificial Atoms Illuminate the Quantum Internet
Quantum dots, tiny semiconductor structures that behave like artificial atoms, have shown immense promise in quantum information technologies. This experiment proves their viability for secure, long-distance quantum communication in practical settings.
Professor Fei Ding of Leibniz University of Hannover explained: “We work with quantum dots, which are tiny structures similar to atoms but tailored to our needs. For the first time, we used these ‘artificial atoms’ in a quantum communication experiment between two different cities. This setup, known as the ‘Niedersachsen Quantum Link,’ connects Hannover and Braunschweig via optical fibre”
The researchers achieved stable and fast transmission of secret keys, verifying positive secret key rates for distances up to 144 km in laboratory conditions. In the real-world deployment, they maintained high-rate secret key transmission with low error rates for 35 hours.
Outperforming Existing QKD Systems
Dr. Jingzhong Yang, the study’s first author, highlighted the significance of their results: “Comparative analysis with existing QKD systems involving SPS reveals that the SKR achieved in this work goes beyond all current SPS based implementations. Even without further optimisation of the source and setup performance it approaches the levels attained by established decoy state QKD protocols based on weak coherent pulses.”
The team believes quantum dots hold great promise for other quantum internet applications, such as quantum repeaters and distributed quantum sensing. Their ability to store quantum information and emit photonic cluster states makes them versatile tools for future quantum networks.
Professor Ding expressed enthusiasm about the future implications of their work: “Some years ago, we only dreamt of using quantum dots in real-world quantum communication scenarios. Today, we are thrilled to demonstrate their potential for many more fascinating experiments and applications in the future, moving towards a ‘quantum internet’.”
This breakthrough comes at a crucial time, as conventional encryption methods face increasing vulnerability to emerging quantum computing technologies. By harnessing the unique properties of quantum physics, QKD offers a path to unbreakable encryption for the digital age.
As research continues, the ‘Niedersachsen Quantum Link’ stands as a testament to the rapid progress in quantum communication. It paves the way for larger, more robust quantum networks that could one day form the backbone of a secure, global quantum internet.
