India has successfully conducted its first demonstration of a free-space quantum key distribution (QKD) link, spanning a distance of over 5.56 kilometers. The project was a collaborative effort between the deep-tech startup QNu Labs, the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N), and IIT Gandhinagar.
Unlike traditional methods that rely on physical fibre-optic cables, free-space QKD transmits secret digital passwords via light particles through open air. This technology leverages the principles of quantum mechanics, ensuring that any unauthorized attempt to intercept or measure the photons alters their state, thereby providing a highly secure data transmission method. This approach is particularly significant for communication across challenging terrains or obstacles where laying cables is not feasible.
The Ministry of Electronics and Information Technology confirmed that the field trial took place on the night of September 27–28, successfully establishing a secure channel between BISAG-N and IIT Gandhinagar. The trial utilized QNu Labs’ pointing, acquisition, and tracking system to maintain a stable quantum bit error rate of less than 5%, generating secure keys at a rate of 230–260 bits per second.
These keys were subsequently integrated into the 'Vedic Kavach' platform, a post-quantum cryptography system developed by BISAG-N, to facilitate end-to-end encryption and decryption of test messages. BISAG-N Director General Vinay Thakur described the integration as a vital advancement toward practical, quantum-resilient communication systems.
Sunil Gupta, co-founder and CEO of QNu Labs, noted that the success of this 5.56 km demonstration establishes a pathway for future long-distance networks and satellite-based quantum communication. Cmde Manish Tripathi (Retd.), in-charge of the ISTF at IIT Gandhinagar, added that the project highlights the effectiveness of combining academic research with indigenous technology to address modern security challenges.
Free-space optics are considered a foundational technology for transmitting keys between Earth and satellites, serving as a critical component for the development of a global, quantum-secure internet. This achievement strengthens India's infrastructure against emerging security threats in the quantum era.
