India and DRDO-IIT Delhi Achieve Milestone in Quantum Secure Communication

India achieved a significant breakthrough in quantum technology on June 16, 2025, as the Defence Research and Development Organisation (DRDO) and IIT Delhi demonstrated successful quantum entanglement-based free-space quantum secure communication over a distance greater than one kilometre. This landmark achievement, executed through the DRDO-Industry-Academia Centre of Excellence (DIA-CoE) at IIT Delhi, places India at the forefront of secure communication technologies vital for future warfare and strategic applications.

The experiment, conducted using a free-space optical link on the IIT Delhi campus, achieved a secure key rate of around 240 bits per second with a quantum bit error rate of less than 7%. This is part of a project named 'Design and development of photonic technologies for free space QKD,' which is supported by the Directorate of Futuristic Technology Management (DFTM), DRDO.

Led by Professor Bhaskar Kanseri's research team, the demonstration was attended by senior 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 experiment utilized an entanglement-assisted approach, offering greater security than conventional methods by ensuring any interception attempt disturbs the quantum state and is detectable.

Quantum communication offers transformative potential across various sectors, such as defence, banking, and telecommunications, by providing fundamentally unbreakable encryption. Free-space Quantum Key Distribution (QKD) is particularly beneficial as it eliminates the need for fiber-optic infrastructure, enabling secure communication even in challenging terrains and urban settings.

Earlier, in 2022, India demonstrated an intercity quantum link between Vindhyachal and Prayagraj using underground dark optical fiber and later conducted a 100-km quantum key distribution experiment via optical fiber in 2024. These ongoing advancements highlight the rapid progress under DRDO's 15 Centres of Excellence established at leading academic institutions for next-generation defence research.

Raksha Mantri Rajnath Singh lauded DRDO and IIT Delhi for this remarkable achievement, describing it as a game-changer in future warfare and national cybersecurity. Dr Samir V Kamat, Secretary Department of Defence R&D and Chairman DRDO, along with IIT Delhi Director Prof Rangan Banerjee, also commended the research team for advancing the boundaries of quantum communication technology.