India Demonstrates 5.56-km Quantum Communication Link, Advancing Secure Network Technology

India has achieved a significant milestone in quantum communication with the successful demonstration of its first free-space Quantum Key Distribution (QKD) link spanning 5.56 km, highlighting the country's progress in developing advanced, indigenous technologies for secure communications.

The field trial was conducted by QNu Labs in collaboration with the Bhaskaracharya National Institute for Space Applications and Geo-informatics (BISAG-N) and IIT Gandhinagar. It established a secure quantum communication channel between BISAG-N and IIT Gandhinagar.

During the demonstration, QNu Labs' Pointing, Acquisition and Tracking system maintained a stable connection, achieving a Quantum Bit Error Rate (QBER) of below 5 per cent and generating secure encryption keys at a rate of 230–260 bits per second.

The generated keys were integrated with BISAG-N's Vedic Kavach platform, which incorporates post-quantum cryptography. The system successfully completed end-to-end encryption and decryption of test messages, demonstrating the practical application of the combined security technologies.

The architecture brought together two complementary approaches to quantum-resistant communication. QNu Labs' Armos device used hardware-based QKD over free-space optical channels, while BISAG-N's Vedic Kavach platform provided software-based post-quantum cryptography supported by quantum random number generation.

Dr Vinay Thakur, Director General of BISAG-N, described the integration of Vedic Kavach with QNu Labs' QKD technology as an important step towards building practical communication systems capable of withstanding future quantum-era security threats.

The demonstration also establishes a foundation for expanding India's secure communication infrastructure. As advances in quantum computing threaten to undermine some of today's widely used encryption methods, quantum-resistant technologies are emerging as an important component of long-term digital security.

Sunil Gupta, Co-founder and CEO of QNu Labs, said the successful 5.56-km trial opens up possibilities for developing longer-distance quantum-secure networks and exploring satellite-based quantum communication.

The integrated system is designed to provide an additional layer of resilience, ensuring that secure communication can continue even when the physical quantum channel is temporarily unavailable.

Cmde Manish Tripathi (Retd.), In-charge of ISTF at IIT Gandhinagar, said the demonstration offered a valuable real-world testing environment for advancing practical quantum communication technologies. He highlighted the importance of bringing together academic research, indigenous technological capabilities and field experimentation to address emerging security requirements.

Founded in 2016, QNu Labs develops quantum-secure digital infrastructure and provides indigenous security products and solutions deployed globally.

BISAG-N, an autonomous scientific society under the Ministry of Electronics and Information Technology (MeitY), works in areas including space technology applications, satellite communication and geo-informatics. It also supports technology-driven governance initiatives.

The successful trial marks a step forward in India's efforts to develop homegrown quantum communication capabilities, with potential applications in critical infrastructure, government networks and other sectors where secure data transmission is essential.