India demonstrates first free-space quantum link for secure communications

India has successfully demonstrated its first free-space Quantum Key Distribution (QKD) link over a distance of 5.56km, marking a step towards strengthening secure communications against emerging quantum-era security threats.

The field trial was conducted by QNu Labs, an Indian quantum-secure digital infrastructure company, in collaboration with the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N) and the Indian Institute of Technology Gandhinagar, according to an official statement issued yesterday (3 October).

The trial, conducted on the night of 27-28 September, established a secure quantum communication channel between BISAG-N and IIT Gandhinagar.

Using QNu Labs' Pointing, Acquisition and Tracking system, the trial achieved a stable Quantum Bit Error Rate of below 5% and generated secure keys at a rate of 230-260 bits per second.

The keys were integrated with BISAG-N's post-quantum cryptography-enabled Vedic Kavach platform, allowing test messages to be encrypted and decrypted successfully from end to end.

The demonstration combined two layers of quantum security: QNu Labs' hardware-based QKD device, Armos, which operates over free-space optical channels, and BISAG-N's software-based post-quantum cryptography system with quantum random number generation.

The integrated architecture is designed to maintain security even when the physical quantum channel is temporarily unavailable.

Vinay Thakur, director general of BISAG-N, said integrating its software with QNu Labs' QKD technology marks a significant step towards developing practical quantum-resilient communication systems.

Sunil Gupta, co-founder and CEO of QNu Labs, said the 5.56km demonstration could pave the way for longer-distance quantum-secure networks and satellite-based quantum communications.