Light itself became the lock: India beams unhackable codes across 5.56 km of open sky

On the night of September 27–28, engineers from QNu Labs, BISAG-N and IIT Gandhinagar shone a laser across 5.56 km of open air and used it to swap secret codes made of light itself — India's first free-space quantum key link. The trick: quantum keys are woven from particles of light, so any eavesdropper physically disturbs them and spying becomes instantly visible. The trial kept errors under 5% and generated 230–260 secret bits per second, then plugged those keys into BISAG-N's "Vedic Kavach" post-quantum system — a working blueprint for hack-proof government and banking messages.