QKD-over-MCF: India’s ‘quantum’ leap towards digital sovereignty

By Dr Jaijit Bhattacharya & Anushka Verma

In a world where sensitive data, from military communications to financial transactions, faces unprecedented cybersecurity threats, India has taken a significant step towards guaranteeing unhackable security. The country recently reached a watershed moment when it successfully demonstrated Quantum Key Distribution (QKD), a method of secure communication, using an advanced fibre optic cable known as Multi-Core Fibre (MCF).

But why is QKD critical for modern communication? The answer is simple: it ensures ultra-secure communication by harnessing the principles of quantum physics to exchange encryption keys, such as passwords, between two parties.

What sets QKD apart is its ability to detect any attempt at interception or tampering in real time. If an unauthorised party tries to access the key, the system immediately raises an alert. This makes QKD a groundbreaking technology for ensuring sensitive information remains protected in the digital world. This technology is especially critical for sectors such as defence, banking, and healthcare, where protecting sensitive information is paramount.

This achievement, driven by the partnership between Sterlite Technologies Limited (STL) and the Centre for Development of Telematics (C-DOT), marks a significant step forward in advancing India's technological autonomy and cybersecurity goals, closely aligned with the national initiatives of Atmanirbhar Bharat and Make in India.

MCF Innovation for Quantum Security

India’s breakthrough lies in utilising MCF, an advanced fibre optic cable that functions like multiple lanes inside a single road, enabling more data to travel without requiring additional space. Traditionally, QKD required a dedicated fibre line. But India was able to demonstrate that quantum keys can be transmitted securely alongside regular data within the same cable, eliminating the need for separate infrastructure.

In a successful test, Indian telecom manufacturers transmitted quantum keys over 100 kilometres using a four-core MCF. One core carried the quantum keys; the other three handled high-speed data. This achievement demonstrates that quantum security can be integrated into real-world networks without compromising performance, offering a cost-effective and scalable solution.

India’s success with QKD over Multi-Core Fibre places it among these front runners, proving that India can compete at the highest level of technological innovation.

By demonstrating that quantum-secure communication can run on MCF alongside regular data, India can now avoid the huge cost of laying separate cables just for quantum networks. This benefits a wide range of applications, from banking and government communications to healthcare and national defence. It also gives India a strategic edge in cybersecurity, reducing dependence on foreign technology and lowering the risk of hidden vulnerabilities.

India’s Presence in the Quantum Communications Race

India’s successful QKD-over-MCF trial comes amid a global race for quantum-secure communication dominance. China leads with its vast 12,000 km quantum network and satellites, such as Micius, which integrates QKD across cities and sectors. Europe is building the EuroQCI network to protect government and institutional data using its own QKD systems, aiming for full rollout by 2030. The US focuses on pilot networks and developing post-quantum algorithms for broader cybersecurity.

Post-quantum algorithms are new encryption methods designed to withstand attacks from quantum computers, ensuring that even traditional systems remain secure in the era of quantum.

India can pilot a quantum-secured network corridor, for instance, between New Delhi and Mumbai or linking critical defence installations.

India’s success with QKD over Multi-Core Fibre places it among these front runners, proving that India can compete at the highest level of technological innovation. Looking ahead, India’s success opens the door to exporting homegrown quantum-secure solutions to friendly countries, strengthening both trade and global partnerships while showcasing Indian innovation to the world.

Strategic Advantages and the Road Ahead

The successful QKD-over-MCF trial is not an end, but a beginning. It opens multiple future pathways for India’s quantum communication roadmap, leveraging this foundation to broader advantage.

As India rolls out 5G and plans for 6G, there is an opportunity to build quantum security into next-generation telecom from the ground up. Researchers envision that technologies like QKD will enhance the security of 6G networks and beyond. The multi-core fibre approach could allow cell towers, network cores, and data centres to exchange quantum keys alongside classical data, securing mobile communications and Internet-of-Things backbones against interception.

India can pilot a quantum-secured network corridor, for instance, between New Delhi and Mumbai or linking critical defence installations. Over time, a larger quantum-secure fibre network could emerge, possibly as part of India’s recently launched National Quantum Mission. That mission envisages a secure quantum communications network and even a satellite, which India plans to launch by around 2026 to enable encrypted links over much longer distances. Combining terrestrial MCF-based QKD with satellite QKD would give India a fully integrated quantum communication infrastructure covering vast distances, a model already being pursued by China.

The innovation carries significant export potential. Many countries, especially those in the developing world or smaller nations, will seek quantum-safe communication solutions but may be deterred by the high cost of bespoke systems. India’s integrated QKD framework, utilising standard telecom fibres upgraded with multi-core technology, could be an attractive and affordable offering. If Indian firms can commercialise this solution, India will dominate the growing global QKD market, which is projected to expand from about USD 485 million in 2024 to USD 2.6 billion by 2030.

Towards a Secure and Sovereign Digital Future

As global powers race to build quantum-secure networks, India has signalled that it will not be left behind; in fact, it may chart a unique path that others can learn from, balancing innovation, cost efficiency, and strategic self-reliance. Industry stakeholders and government officials can take confidence in this achievement as a sign that India’s quantum ecosystem is coming of age.

The task ahead is to expand and implement this vision widely, turning the demonstrated technology into a deployed reality across the nation’s networks. If executed well, India’s quantum-secured fibre networks could become the bedrock of secure communications in the coming decades, supporting defence, finance, healthcare, governance and beyond with the assurance that sensitive data remains for our eyes only, no matter how advanced the threat. It is a future where Digital India is not just connected and fast, but also quantum-secure.

Jaijit (left) and Anushka (right) are associated with the Centre for Digital Economy Policy (C-DEP) as its President and Policy Consultant, respectively.