Centre for Development of Telematics (C-DOT) and Sterlite Technologies Limited (STL) have successfully tested India’s first quantum key distribution (QKD) transmission over a four core multi-core fibre (MCF), marking a major milestone in the nation’s journey towards quantum-secured communication networks.
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 single fibre. This allows for the simultaneous transmission of QKD and high-capacity data traffic on a single fibre without compromising quantum signal integrity thereby saving fibre cost.
In this activity, the quantum signals of QKD were transmitted through one core, while simultaneously, the 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.