India demonstrates its first 5.56 km free-space quantum key link
India has demonstrated its first free-space quantum key distribution link — 5.56 km between BISAG-N and IIT Gandhinagar — with quantum-secured keys encrypting test messages, the government announced on Oct 3.
Bengaluru-based QNu Labs ran the quantum hardware on its Armos system, holding the quantum bit error rate under 5% and producing secure keys at 230–260 bits per second, according to the announcement.
BISAG-N fed the keys into its own post-quantum platform, Vedic Kavach, which used them to encrypt and decrypt test messages — a full loop from quantum transmission to practical use.
The distance is short by fibre standards, but the medium is the point: the keys crossed open air rather than a cable, a step toward satellite-based quantum-secure communication for defence, finance and critical infrastructure.
