India demonstrates first 5.56 km free-space Quantum Key Distribution link
India has achieved a major breakthrough in quantum communications with the successful demonstration of its first free-space Quantum Key Distribution (QKD) link spanning 5.56 km. The field test, conducted on 27-28 September 2026 between BISAG-N and IIT Gandhinagar sites, was completed by QNu Labs in collaboration with Bhaskaracharya National Institute for Space Applications and Geo-informatics and IIT Gandhinagar.
The system used QNu's Pointing, Acquisition and Tracking device and Armos QKD equipment to maintain a stable Quantum Bit Error Rate below 5% while generating secure keys at 230–260 bits per second. The generated keys were integrated into BISAG-N's post-quantum cryptography-enabled Vedic Kavach platform, successfully enabling end-to-end encryption and decryption of test messages, according to the Ministry of Electronics.
Free-space QKD transmits quantum signals through the open atmosphere as a narrow optical beam, eliminating the need for optical fibre infrastructure while introducing challenges related to alignment, turbulence, and background light.
