India has taken a significant step towards developing quantum-secure communication networks with the successful testing of a 5.56-km open-air quantum key distribution link between BISAG-N and IIT Gandhinagar.
The trial was conducted on the night of September 27-28 by QNu Labs in collaboration with BISAG-N and IIT Gandhinagar. During the demonstration, quantum-encoded light was transmitted between the two facilities, located 5.56 km apart, to assess the reliability of quantum communication through the atmosphere.
The successful test demonstrates the potential of quantum key distribution, or QKD, for establishing secure communication channels over terrestrial links. QKD uses the principles of quantum mechanics to generate and distribute encryption keys, with the properties of quantum states enabling attempts to intercept the communication to be detected.
The demonstration is also significant for India’s broader ambitions in space-based quantum communication. The Indian Space Research Organisation (ISRO) is working towards technologies that could enable secure quantum communication between satellites and ground stations, as well as between satellites.
Such capabilities could form an important component of future secure communication infrastructure, particularly for applications requiring high levels of protection against interception and cyber threats.
The effort is aligned with the objectives of India’s National Quantum Mission, which seeks to advance the country’s capabilities in quantum computing, communication, sensing and related technologies. Developing reliable quantum communication links on the ground is an important step towards addressing the technical challenges involved in extending the technology to space.
The latest demonstration also provides an opportunity to study the performance of quantum signals under atmospheric conditions over several kilometres. Further development will be required to extend the range and reliability of such systems and to adapt them for satellite-based applications.
With ISRO pursuing secure quantum communication from space, successful terrestrial demonstrations such as the 5.56-km link could contribute to the development of a future quantum-secure communication network connecting ground stations and satellites.
