India Successfully Demonstrates First Free-Space Quantum Key Distribution Link Over 5.56 km

India has successfully demonstrated its first free-space Quantum Key Distribution (QKD) link over a distance of 5.56 kilometers. This achievement was realized through the joint efforts of QNu Labs, the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N), and the Indian Institute of Technology (IIT) Gandhinagar.

The field test was conducted on the night of September 27-28, establishing a secure quantum communication channel between BISAG-N and IIT Gandhinagar. The test utilized the pointing, acquisition, and tracking system developed by QNu Labs, achieving a stable quantum bit error rate of less than 5% and generating secure keys at a rate of 230-260 bps.

These secure keys were integrated with BISAG-N's post-quantum cryptography-enabled 'Vedic Kavach' platform, enabling the successful end-to-end encryption and decryption of test messages. The system employs two complementary layers of quantum security: the first layer is QNu Labs' hardware-based QKD device 'Armos', which operates on free-space optical channels, and the second layer is BISAG-N's software-based 'Vedic Kavach' post-quantum cryptography featuring quantum random number generation. This integrated architecture is capable of ensuring security even during the unavailability of the physical quantum channel.

Dr. Vinay Thakur, Director General of BISAG-N, stated that the integration of QNu Labs' QKD technology with 'Vedic Kavach' is a significant step toward a practical quantum-secure communication system. Sunil Gupta, Co-founder and CEO of QNu Labs, noted that this successful demonstration paves the way for long-distance quantum-secure networks and satellite-based quantum communication. Meanwhile, Commodore Manish Tripathi (Retd), in charge of ISTF at IIT Gandhinagar, remarked that the demonstration shows how academia, indigenous technology, and real-world experiments can be integrated to meet emerging secure communication needs.

This test establishes a strong foundation for enhancing India's capabilities in secure communication infrastructure and addressing security threats of the quantum era. BISAG-N is an autonomous scientific institution under the Ministry of Electronics and Information Technology (MeitY), operating in the fields of space technology, satellite communication, and geo-informatics.