Pariksha SaathiIndia's First 5.56 km Free-Space Quantum Key Distribution Link Demonstrated
QNu Labs, working with the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N) and IIT Gandhinagar, has demonstrated a 5.56-km free-space Quantum Key Distribution (QKD) link, described as the first of its kind in India. In a field trial on the night of 27-28 September 2026, the partners set up a secure quantum channel between BISAG-N and IIT Gandhinagar. With QNu Labs' Pointing, Acquisition and Tracking (PAT) system in use, the Quantum Bit Error Rate held steady below 5% and secure keys were produced at 230-260 bits per second. Those keys were then fed into Vedic Kavach, BISAG-N's platform with post-quantum cryptography, which successfully encrypted and decrypted test messages end to end. Pairing QNu Labs' Armos QKD hardware with Vedic Kavach's software-based post-quantum layer is meant to keep communication protected even if the quantum channel drops out temporarily. The partners see the result as a stepping stone towards longer-range and satellite-based quantum-secure networks.
Drafted with AI assistance from the official PIB release linked above and checked against it by a second AI pass. Not line-edited by a human.
Learning context
Quantum Key Distribution (QKD) and post-quantum cryptography (PQC) protect data in different ways. QKD, whose first protocol (BB84) was proposed by Charles Bennett and Gilles Brassard in 1984, sends key bits on quantum states of light; eavesdropping disturbs those states and shows up as a higher Quantum Bit Error Rate. PQC is ordinary software on classical computers, built on mathematical problems believed to be hard even for quantum computers; the US National Institute of Standards and Technology (NIST) released its first three PQC standards, FIPS 203, 204 and 205, in August 2024.
Reference: NIST's Post-Quantum Cryptography project page
Check yourself: does post-quantum cryptography need a quantum channel or quantum hardware?
No. PQC runs on existing classical computers and networks. Only QKD needs a dedicated quantum (optical) link, which is why this demonstration paired QKD hardware with PQC software as a fallback layer.
Revision task: mark which part of the demonstration was hardware QKD (Armos) and which was software PQC (Vedic Kavach), and note why a low Quantum Bit Error Rate matters.
Test yourself
India's first 5.56-km free-space Quantum Key Distribution (QKD) link, demonstrated by QNu Labs and BISAG-N, connected BISAG-N with which institute?
Show the answer
Answer: IIT Gandhinagar
The field trial on the night of 27-28 September 2026 linked BISAG-N and IIT Gandhinagar, with a Quantum Bit Error Rate below 5%; the keys were fed into the Vedic Kavach post-quantum platform.
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