India marked a major milestone in quantum technology on June 16, 2025, as the Defence Research and Development Organisation (DRDO) and IIT Delhi successfully demonstrated quantum entanglement-based free-space quantum secure communication over a distance exceeding one kilometre. Conducted through the DRDO-Industry-Academia Centre of Excellence (DIA-CoE) at IIT Delhi, the achievement positions India at the forefront of secure communication technologies critical for future warfare and strategic applications.
Using a free-space optical link on the IIT Delhi campus, the experiment achieved a secure key rate of approximately 240 bits per second with a quantum bit error rate of less than 7%. This effort is part of the project titled ‘Design and development of photonic technologies for free space QKD,’ sanctioned by the Directorate of Futuristic Technology Management (DFTM), DRDO.
The demonstration was led by Professor Bhaskar Kanseri’s research team and witnessed by top officials including DRDO’s DG (MED, COS & CS), Directors of SAG and DFTM, the Dean (R&D) of IIT Delhi, the DIA-CoE Director, and DRDO scientists. The entanglement-assisted approach used in this experiment offers higher security than traditional methods, ensuring that any interception attempt disturbs the quantum state and is detectable by the system.
Quantum communication holds transformative potential across sectors such as defence, banking, and telecommunications, offering fundamentally unbreakable encryption. Free-space Quantum Key Distribution (QKD) is particularly valuable as it avoids the need for fiber-optic infrastructure, enabling secure communication even in difficult terrains and urban environments.
India had previously demonstrated an intercity quantum link between Vindhyachal and Prayagraj in 2022 using underground dark optical fiber and followed it with a 100-km quantum key distribution experiment via optical fiber in 2024. These continuous advancements underline the rapid strides being made under DRDO’s 15 Centres of Excellence established across top academic institutions for next-generation defence research.
Raksha Mantri Rajnath Singh congratulated DRDO and IIT Delhi for this significant leap, calling it a game-changer in future warfare and national cyber security. Dr Samir V Kamat, Secretary Department of Defence R&D and Chairman DRDO, along with IIT Delhi Director Prof Rangan Banerjee, also extended their appreciation to the research team for pushing the boundaries of quantum communication technology.
