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What I say in the video
India just sent a key that snitches on spies — 5.56 kilometres through open air.
The government calls it Quantum Key Distribution: a secret password sent as bits of light.
Now, picture the seal on a medicine bottle.
It doesn't stop anyone opening it. It shows someone did.
Same here. A spy who peeks changes the light. The errors jump. You toss that key.
In 2021, India's version only crossed 300 metres. This one's 18 times farther — next stop, space.
But why air, not cables? Cables can't reach a satellite.
Here's the thing. Spies can copy your data today and crack it later.
Quantum doesn't stop spies from looking. It makes sure you know they looked.
China did it from space in 2017. India's catching up, and I'm watching.
In plain words
India has demonstrated its first free-space Quantum Key Distribution (QKD) link at a 5.56 km scale, between BISAG-N and IIT Gandhinagar in Gujarat, using QNu Labs hardware (reported 3 Oct 2026).
How QKD works, simply: the key travels as bits of light. An eavesdropper who measures the light disturbs it, the error rate jumps, and the key is thrown away. QKD does not stop tapping; it makes tapping visible. In this trial the error rate stayed below 5%.
For scale: ISRO's 2021 free-space QKD demo covered 300 metres. China's Micius satellite did satellite-to-ground QKD in 2017. Free-space links are the step toward satellite quantum communication.
Sources are in the pinned comment.
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