First Qcom Tests in Lower Saxony over a 79 km long Optical Fiber Connection from Hannover to Braunschweig:
In a major scientific breakthrough, researchers from Leibniz University Hannover (LUH), Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, and the University of Stuttgart have implemented a new method for secure communication using semiconductor quantum dots. This advancement could revolutionize how we protect our confidential information from cyber threats.
Conventional encryption methods rely on complex mathematical algorithms and the limits of current computing power. However, with the rise of quantum computers, these methods are becoming increasingly vulnerable, necessitating quantum key distribution (QKD). QKD is a technology that leverages the unique properties of quantum physics to secure data transmission. By using single photons as carriers of quantum keys, QKD ensures that any attempt to intercept the communication is detected immediately, as it introduces errors in the signal. This method has been continuously optimized over the years, but establishing large networks has been challenging due to the limitations of existing quantum light sources.
The team, led by Professors Fei Ding, Stefan Kück, and Peter Michler, has made significant strides in this field. They used semiconductor quantum dots as single-photon sources, achieving high secure key transmission rates over a 79-kilometer distance between Hannover and Braunschweig. This is the first quantum communication link in Lower Saxony.
Figure: Distribution of quantum bits between Leibniz University of Hannover (Alice) and PTB Braunschweig (Bob) over 79 km of deployed fibre with a total loss of 25.49 dB. Map data from Google (©2023 Google). Credit: Light: Science & Applications (2024).
Professor Fei Ding explained the breakthrough: “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 fiber.”
The need for secure communication is as old as humanity itself. Quantum communication uses the quantum characteristics of light to ensure that messages cannot be intercepted. “Quantum dot devices emit single photons, which we control and send to Braunschweig for measurement. This process is fundamental to quantum key distribution,” Ding explained. He expressed his excitement about the outcome of this collaborative effort: “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’.”
Click here to see the article titled “High-rate intercity quantum key distribution with a semiconductor single-photon source” published in Light: Science & Applications.
Figure: Flying single photons emitted from a quantum dot are coupled into a field-based deployed fibre in the city of Hannover, Germany, and sent to Braunschweig, Germany. Credit: Light: Science & Applications (2024).
Funding:
1. German Federal Ministry of Education and Research (BMBF) – QR.X, SQuaD and SemIQON
2. European Research Council Consolidator Grant – MiNet
3. European Union’s Horizon 2020 research and innovation program – Qurope
4. EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme – SEQUME
5. German Research Foundation (DFG) – InterSync
6. Germany’s Excellence Strategy – Quantum Frontiers
7. Flexible Funds programme by Leibniz University Hannover
Authors: Jingzhong Yang, Michael Zopf
Author of the illustrations: © Dan Huy Chau, Jingzhong Yang
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