New Delhi, June 17, 2025: In a groundbreaking scientific achievement, Indian scientists have successfully demonstrated quantum entanglement-based free-space secure communication over a distance of more than one kilometre via an optical link. The development, made possible by the Defence Research and Development Organisation (DRDO)-Industry-Academia Centre of Excellence (DIA-CoE), IIT Delhi, has ushered in a new quantum era in the country.
The experiment achieved a secure key rate of 240 bits per second with a low error rate. This was not just a simulation; it was done in real-world conditions, showcasing the practical viability of quantum communication alongside traditional data transmission.
"This entanglement-assisted quantum secure communication paves the way for real-time applications in quantum cyber security, including long-distance Quantum Key Distribution (QKD), the development of quantum networks, and the future quantum internet," the Ministry of Defence stated.
Union Defence Minister Rajnath Singh also congratulated DRDO and IIT-Delhi for the achievement, showcasing India’s rapid advancements in the field, "which will be game changer in future warfare".
Notably, the project ‘Design and development of photonic technologies for free space QKD’ was sanctioned by the Directorate of Futuristic Technology Management (DFTM), DRDO, while Prof Bhaskar Kanseri’s research team demonstrated the test.
A breakthrough has been achieved by demonstrating quantum entanglement based communication in an experimental setup through DRDO-Industry-Academia Centre of Excellence (DIA-CoE), IIT Delhi. The free-space quantum secure communication using quantum entanglement over a distance of…
— DRDO (@DRDO_India) June 16, 2025
What is quantum entanglement?
In simple terms, quantum communication involves sending information from one place to another using something called "quantum entanglement". Think of quantum entanglement like an invisible twin connection where two particles, even if miles apart, are linked in a way that what happens to one instantly affects the other. Unlike sending a physical object, you are sending the state or condition of a particle.
Benefits of quantum communication
* Unbreakable encryption makes it a dual-use technology with applications in securing data in strategic sectors such as defence, finance, and telecommunications.
* Protecting national security-related communications.
* Free-space QKD eliminates the need to lay optical fibres, making it less expensive.
* Can be deployed in challenging terrains and dense urban environments.
Previous breakthroughs
Last year, in another DRDO-supported project, the scientists successfully distributed quantum keys using entanglement over a 100 km spool of telecom-grade optical fibre. Meanwhile, in 2022, the country’s first intercity quantum communication link between Vindhyachal and Prayagraj was established using commercial-grade underground dark optical fibre.