No Fibre, Just Photons: India Tests a New Route to Quantum-Secure Networks

India has crossed an important milestone in quantum communication, demonstrating a secure link that transmitted encryption keys across 5.56 kilometres of open air instead of relying on a physical fibre-optic cable.

The field trial was conducted by Bengaluru-based deeptech startup QNu Labs in collaboration with BISAG-N and IIT Gandhinagar on the night of September 27–28. The link connected BISAG-N with IIT Gandhinagar using QNu Labs’ free-space Quantum Key Distribution technology and its Pointing, Acquisition and Tracking system.

During the demonstration, the system maintained a quantum bit error rate below 5% and generated secure cryptographic keys at 230–260 bits per second. These keys were then integrated with BISAG-N’s post-quantum cryptography-enabled Vedic Kavach platform, allowing test messages to be successfully encrypted and decrypted end to end.

What makes the experiment significant is the absence of fibre between the two locations. Quantum Key Distribution uses properties of quantum particles to exchange cryptographic keys, with attempts to measure the transmitted quantum states capable of revealing interference. Free-space transmission allows these optical links to cross terrain or obstacles where laying fibre may be difficult, while also serving as a building block for future ground-to-satellite quantum communication.

The trial combined QNu Labs’ hardware-based Armos QKD system with Vedic Kavach’s software-based post-quantum protection and quantum random number generation. That layered architecture is designed to maintain security even if the physical quantum channel is temporarily unavailable. While the 5.56-kilometre experiment remains a ground-based field demonstration rather than a satellite network, it gives India a practical testbed for extending quantum-secure communication over longer distances — and eventually towards space-based links.