India demonstrates 5.56-km free-space quantum key distribution link
New Delhi, Oct 4. India has successfully demonstrated a 5.56-km free-space Quantum Key Distribution (QKD) link, marking a significant step towards the development of secure quantum communication networks and satellite-based quantum communications.
The field demonstration was carried out by QNu Labs in collaboration with the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N) and IIT Gandhinagar during the night of September 27-28. It established a secure quantum communication channel between BISAG-N and IIT Gandhinagar.
The trial used QNu Labs’ Pointing, Acquisition and Tracking (PAT) system and achieved a stable Quantum Bit Error Rate (QBER) of below 5 percent. It generated secure cryptographic keys at a rate of 230-260 bits per second, which were subsequently integrated with BISAG-N’s post-quantum cryptography-enabled Vedic Kavach platform.
The integration enabled successful end-to-end encryption and decryption of test messages, demonstrating the ability to combine quantum and post-quantum security technologies in a practical communication environment.
The demonstration brought together two complementary layers of quantum security. QNu Labs’ Armos hardware-based QKD system transmitted quantum keys over a free-space optical channel, while BISAG-N’s Vedic Kavach provided software-based post-quantum cryptography along with quantum random number generation.
According to the Ministry of Electronics and Information Technology, the combined architecture is designed to maintain security even when the physical quantum communication channel is temporarily unavailable, thereby adding resilience to quantum-secure communication networks.
BISAG-N Director General Vinay Thakur said the integration of Vedic Kavach with QNu Labs’ QKD technology represented an important step towards developing practical quantum-resilient communication systems.
QNu Labs co-founder and CEO Sunil Gupta said the 5.56-km demonstration could pave the way for longer-distance quantum-secure networks as well as future satellite-based quantum communication systems.
Cmde Manish Tripathi (Retd.), who is in charge of the Indian Space Technology and Finance (ISTF) initiative at IIT Gandhinagar, said the demonstration provided a field environment for advancing practical quantum communication technologies. He also highlighted the role of collaboration between academia and indigenous technology developers in addressing emerging secure-communications requirements.
The successful trial is expected to provide a foundation for further development of India’s secure communication infrastructure and strengthen its preparedness against security threats arising from advances in quantum computing.
BISAG-N, an autonomous scientific society under the Ministry of Electronics and Information Technology, works in areas including space technology applications, satellite communications and geo-informatics, besides supporting technology-driven governance.
IIT Gandhinagar, established in 2008, undertakes research and education across engineering, science, technology, humanities and social sciences, with a focus on interdisciplinary research and solutions to real-world challenges.
QNu Labs, founded in 2016, develops quantum-secure digital infrastructure and indigenous quantum communication and security technologies.
