STL and C-DOT successfully demonstrate India’s first Quantum Key Distribution with Multi-Core Fibre

STL in collaboration with the Centre for Development of Telematics (C-DOT) has announced the successful demonstration of India’s first Quantum Key Distribution (QKD) transmission over 100 kms, 4-core Multi-Core Fibre (MCF) network. This landmark achievement marks a significant step in building India’s first quantum-secured, future-ready communication networks.

As a leading provider of advanced connectivity solutions for digital infrastructure, including Optical Networking, Optical Connectivity, Data Centres, and Enterprise solutions, STL has designed, developed and deployed India-first Multi-Core Fibre (MCF) cable (aerial and underground network) as an end-to-end solution, spanning cabling, connectivity, installation, and deployment. STL’s field-deployable MCF cabling technology was deployed in the Department of Telecommunications (DoT)-sponsored Advanced Optical Communications (AOC) Test Bed at IIT-Madras, complying with Essential Requirements (ER) led by TEC standards. STL is the first company in the world that has taken a position on deploying MCF cables in both underground and aerial network infrastructures. It is now leading efforts in the standardisation of fibre and cable and their test & measurement technologies globally. This positions STL at the forefront of building high-capacity, future-ready optical infrastructure.

MCF technology provides a powerful solution by enabling data transmission across multiple cores within a single fibre, significantly saving physical space and infrastructure costs. In the context of QKD, which typically requires a dedicated dark fibre for the quantum channel, MCF offers a significant advantage - it enables the physical separation of quantum and classical signals into distinct cores within a single fibre. This allows for the simultaneous transmission of QKD and high-capacity data traffic without compromising quantum signal integrity.

By integrating QKD with MCF, STL and C-DOT have addressed two critical challenges in quantum communication - the need for dedicated dark fibre, further improving the cable’s form factor and the ability to handle exponentially growing data traffic.

With this development, STL and C-DOT have reaffirmed their commitment to enabling a secure, scalable, and resilient quantum communication network for India, paving the way for a digitally sovereign future powered by advanced optical and quantum technologies.

Speaking at the occasion, Dr. Rajkumar Upadhyay, CEO of C-DOT, stated, “This initiative is a key milestone for India’s telecom ecosystem. We are glad to have innovative partners like STL in India’s fiberization journey. This achievement clearly establishes the feasibility of integrated-classical networks over next-generation optical fibres, saving costs for QKD deployments drastically.”

Commenting on this achievement, 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. We have demonstrated how cutting-edge optical innovations can revolutionise secure communication by successfully integrating QKD with our indigenously developed MCF. This first in India milestone is a testament to the power of public-private partnerships in building a digitally sovereign and secure nation.”