By successfully integrating QKD with indigenously-developed MCF, the country has demonstrated how cutting-edge optical innovations can revolutionize secure communication, showing India’s growing prowess in pioneering next-gen digital infrastructure.

Apr 17, 2025

In a landmark achievement, Sterlite Technologies Limited (STL), in collaboration with C-DOT, has successfully tested India’s first QKD transmission over a 4-core Multi-Core Fibre (MCF), marking a major milestone in the nation’s journey towards quantum-secured communication networks.

The technology provides a powerful solution by enabling data transmission across multiple cores within a single fibre, significantly saving physical space and infrastructure costs. Quantum Key Distribution (QKD) typically requires a dedicated dark fibre for the quantum channel.

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MCF offers a significant advantage as it enables physical separation of quantum and classical signals into distinct cores within single fibre. This allows for simultaneous transmission of QKD and high-capacity data traffic on a single fibre without compromising on quantum signal integrity, thereby saving fibre cost.

In this activity, the quantum signals of QKD were transmitted through one core, while simultaneously, other three cores on the same fibre were used to carry high-speed user data. A stable QKD link was established over a distance exceeding 100 km, validating the robustness and stability of quantum communication even amidst high-capacity classical data traffic.

The Centre for Development of Telematics (C-DOT), India’s premier telecom R&D centre under the Department of Telecommunications (DoT), Ministry of Communications, Government of India, has successfully developed and deployed industry-grade Quantum Key Distribution (QKD) systems.

Speaking on the occasion, Dr. Rajkumar Upadhyay, CEO of C-DOT, said, “This initiative is a key milestone for India’s telecom ecosystem. This achievement clearly establishes the feasibility of integrated quantum-classical networks over next-generation optical fibres saving costs for QKD deployments drastically”.

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Rahul Puri, CEO, Optical Networking Business, STL said: “This breakthrough collaboration with C-DOT underscores India’s growing prowess in pioneering next-gen digital infrastructure. By successfully integrating QKD with our indigenously developed MCF, we have demonstrated how cutting-edge optical innovations can revolutionize secure communication. We are committed to advancing India’s quantum communication ambitions while driving global optical leadership.’’