India Demonstrates 5.56-Km Free-Space Quantum Key Distribution Link

The field trial established a secure quantum communication channel between the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N) and IIT Gandhinagar. The demonstration was conducted on the night of September 27-28 by QNu Labs in collaboration with the two institutions.

The trial used QNu Labs' Pointing, Acquisition and Tracking system to maintain the optical connection between the two locations. The system recorded a stable Quantum Bit Error Rate (QBER) of below five per cent while generating secure cryptographic keys at a rate of 230-260 bits per second.

The keys were subsequently integrated with BISAG-N's Vedic Kavach platform, which incorporates post-quantum cryptography. This enabled the teams to carry out end-to-end encryption and decryption of test messages.

The demonstration combined two different layers of quantum security. QNu Labs' Armos QKD hardware transmitted quantum keys through a free-space optical channel, while Vedic Kavach provided software-based post-quantum protection and quantum random number generation.

The combined system is designed to maintain security even when the quantum communication link is temporarily unavailable, providing an additional layer of resilience for secure communications.

BISAG-N Director General Vinay Thakur described the integration of Vedic Kavach with QNu Labs' QKD technology as an important development towards practical quantum-resilient communication systems.

QNu Labs Co-founder and CEO Sunil Gupta said the 5.56-km demonstration could help pave the way for longer-range quantum-secure networks and satellite-based quantum communication.

Cmde Manish Tripathi (Retd), who is in charge of the Indian Space Technology and Finance-related activities at IIT Gandhinagar, said the field trial provided an opportunity to test quantum communication technology under practical conditions. He highlighted the role of collaboration between academia and indigenous technology developers in addressing emerging secure communication requirements.

Unlike fibre-based QKD, free-space quantum communication sends quantum signals through open-air optical channels. This makes it potentially useful in locations where laying fibre-optic infrastructure is difficult or impractical.

The technology could also support future long-distance and satellite-based quantum communication systems, where secure transmission across large distances is a key challenge.

The latest demonstration provides a foundation for further development of India's quantum-secure communications infrastructure as governments and technology companies prepare for security challenges associated with increasingly powerful quantum computers.

BISAG-N, an autonomous scientific society under the Ministry of Electronics and Information Technology, works on applications involving space technology, satellite communication and geo-informatics. IIT Gandhinagar, established in 2008, conducts research and education across engineering, science, technology, humanities and social sciences.

QNu Labs, founded in 2016, develops quantum-security technologies and products focused on protecting digital communications against emerging quantum-era threats.