India successfully demonstrates free-space quantum communication
NEW DELHI: India has successfully demonstrated its first free-space Quantum Key Distribution (QKD) link over a distance of 5.56 kilometres, marking a significant step towards building quantum-secure communication networks that can operate beyond traditional fibre-optic cables.
The field trial, conducted on the night of 27-28 September 2026, was carried out by QNu Labs in collaboration with the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N) and IIT Gandhinagar.
The Ministry of Electronics and Information Technology announced the achievement on Saturday, describing it as an important milestone in developing indigenous quantum-resilient communication systems.
How the Trial Was Conducted
A secure quantum communication channel was established between the BISAG-N campus and IIT Gandhinagar using QNu Labs’ Pointing, Acquisition and Tracking (PAT) system.
The demonstration employed QNu Labs’ hardware-based QKD device, Armos, which transmitted quantum signals through free-space optical channels in open air rather than through optical fibre.
The trial achieved a stable Quantum Bit Error Rate (QBER) of below 5 per cent and generated secure encryption keys at a rate of 230–260 bits per second.
These keys were then integrated with BISAG-N’s post-quantum cryptography-enabled Vedic Kavach platform, enabling successful end-to-end encryption and decryption of test messages.
Two-Layer Security Architecture
The system combined two complementary layers of security. The first was the hardware-based free-space QKD link provided by QNu Labs’ Armos device.
The second was the software-based Vedic Kavach platform developed by BISAG-N, which incorporates post-quantum cryptography and quantum random number generation.
This integrated architecture is designed to maintain security even if the physical quantum communication channel becomes temporarily unavailable.
Dr. Vinay Thakur, Director General of BISAG-N, said: “The integration of Vedic Kavach with QNu Labs’ QKD technology marks a significant step towards practical quantum-resilient communication systems.”
Significance of Free-Space QKD
Unlike fibre-based QKD, free-space QKD transmits cryptographic keys through the atmosphere. This approach is particularly relevant for extending quantum-secure links over longer distances and for future satellite-based quantum communication systems, where signals must travel through free space between ground stations and satellites.
Sunil Gupta, Co-founder and CEO of QNu Labs, noted that the successful 5.56-km demonstration could support the development of longer-distance quantum-secure networks and satellite-based quantum communication.
Cmde Manish Tripathi (Retd.), In-charge of the ISTF at IIT Gandhinagar, said the trial provides a real-world field environment that brings together academic research, indigenous technology and practical testing.
BISAG-N is an autonomous scientific society under the Ministry of Electronics and Information Technology specialising in satellite communication, space technology applications and geo-informatics. QNu Labs, founded in 2016, focuses on developing quantum-secure digital infrastructure.
The government stated that the trial lays a foundation for strengthening India’s secure communication infrastructure and for developing systems capable of addressing emerging cybersecurity risks in the quantum computing era.
The successful demonstration of a stable free-space QKD link represents an important indigenous capability that can be scaled for terrestrial networks and, eventually, for space-based quantum communication.
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