QNu Labs takes quantum security beyond fibre with 5.56-km free-space link
Unlike QKD systems that operate over optical fibre, the demonstration transmitted quantum keys through free space between two locations
Deep-tech cybersecurity company QNu Labs has demonstrated its first 5.56-km free-space Quantum Key Distribution (QKD) link, developed in collaboration with BISAG-N and IIT Gandhinagar, marking a step towards quantum-secure communication beyond conventional fibre networks and potentially satellite-based links.
Unlike QKD systems that operate over optical fibre, the demonstration transmitted quantum keys through free space between two locations. QNu Labs used a specialised Pointing, Acquisition and Tracking (PAT) system to maintain precise laser alignment between the two endpoints, enabling photons to travel directly through the atmosphere.
The demonstration brought together two layers of quantum security. QNu Labs deployed its hardware-based Armos QKD system over the free-space optical channel, while BISAG-N contributed Vedic Kavach, a software-based post-quantum cryptography system with quantum random number generation. The architecture is designed to provide an additional layer of protection if the physical quantum channel is temporarily unavailable.
The free-space capability is significant for applications where laying or accessing dedicated optical fibre is difficult, including long-distance and potentially satellite-based communication. QKD uses the properties of quantum mechanics to generate and distribute encryption keys, with attempts to intercept the quantum signal capable of disturbing the transmission.
The demonstration builds on QNu Labs’ work under the National Quantum Mission (NQM), under which the company deployed a live 1,000-km inter-city quantum-secure network in April 2026. That network operates as an overlay on existing telecom fibre infrastructure, using multiple trusted nodes to extend the reach of QKD. A single hardware unit can transmit keys over roughly 150–200 km, after which the keys are passed through additional nodes to cover longer distances.
QNu Labs has raised ₹200 crore in its Series A1 round, led by the National Quantum Mission and Speciale Invest, with participation from Sony Innovation Fund, Gaja Capital and Artha Ventures.
