C-DOT and STL achieves secure communication breakthrough with quantum key distribution Over multi-core fibre

The C-DOT, in collaboration with STL, has successfully tested India’s first Quantum Key Distribution transmission over a 4-core Multi-Core Fibre (MCF). This milestone marks a significant advancement in the nation's journey towards quantum-secured communication networks.
MCF technology enables data transmission across multiple cores within a single fibre, significantly reducing physical space and infrastructure costs. In the context of QKD, which typically requires a dedicated dark fibre for the quantum channel, MCF offers a substantial advantage by allowing the physical separation of quantum and classical signals into distinct cores within a single fibre. This innovation permits the simultaneous transmission of QKD and high-capacity data traffic on a single fibre without compromising the integrity of the quantum signal, thereby saving on fibre costs.

During the testing, quantum signals of QKD were transmitted through one core, while the other three cores on the same fibre carried high-speed user data. A stable QKD link was established over a distance exceeding 100 km, demonstrating the robustness and stability of quantum communication even amidst high-capacity classical data traffic.

C-DOT, India’s premier telecom R&D centre under the Department of Telecommunications, Ministry of Communications, has emerged as a key player in advancing India’s quantum communication ecosystem. C-DOT has successfully developed and deployed industry-grade QKD systems, which have received Technology Approval from the Telecommunication Engineering Centre, a body under the DoT.

STL is a leading global provider of integrated digital networks, specializing in optical fibre manufacturing and network designs. With over 10 global manufacturing plants and a customer base spanning more than 100 countries, STL is at the forefront of building future-ready, scalable fibre networks. STL’s Multi-Core Fibre leverages Space Division Multiplexing in 7 and 4 core fibres to achieve ultra-high transmission capacity per fibre within the same diameter.
Dr. Rajkumar Upadhyay, CEO of C-DOT, stated, “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, drastically reducing costs for QKD deployments.”
Rahul Puri, CEO of Optical Networking Business at STL, added, “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. This milestone is a testament to the power of public-private partnerships in building a digitally sovereign and secure nation.”

Both C-DOT and STL reaffirm their commitment to advancing India's capabilities in quantum communication and optical network innovations. This achievement is a foundational step toward realizing a cost-effective, secure, and resilient national quantum communication infrastructure.

Source: PIB

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