India has taken another step towards quantum-secure communication after scientists and technology researchers successfully demonstrated a 5.56-km quantum link through open air.
The trial was conducted by QNu Labs in collaboration with the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N) and IIT Gandhinagar. The experiment established a secure quantum communication channel between BISAG-N and IIT Gandhinagar.
How Does the Quantum Link Work?
The technology uses Quantum Key Distribution (QKD) to exchange encryption keys through free space rather than relying on a physical fibre-optic cable.
QKD uses properties of quantum physics to detect attempts to intercept the exchanged information. In the demonstration, the system achieved a quantum bit error rate below 5% and generated secure keys at about 230–260 bits per second.
Why Is the 5.56-km Test Important?
Free-space quantum communication could be useful in locations where installing fibre cables is difficult. It could also become an important technology for connecting ground stations with satellites.
The demonstration is therefore being viewed as a step towards longer-distance quantum-secure networks and future satellite-based quantum communication.
The generated keys were also integrated with BISAG-N’s post-quantum cryptography-enabled Vedic Kavach platform, allowing encrypted test messages to be sent and decoded successfully.
The Bigger Picture
Quantum communication is still an emerging technology, but experiments like this are helping researchers understand how secure quantum links can operate outside controlled laboratory environments.
The 5.56-km trial provides a foundation for developing longer-range systems that could eventually support more secure communications between locations on Earth and in space.
