India has marked a significant milestone in quantum technology with a successful demonstration of quantum entanglement-based secure communication, conducted by the DRDO-Industry-Academia Centre of Excellence (DIA-CoE) at IIT Delhi. The trial, achieved over a free-space optical link on the IIT Delhi campus, demonstrated secure quantum communication over a distance of more than one kilometre. 

 

The experiment achieved a secure key rate of approximately 240 bits per second, with a quantum bit error rate of under 7%. This entanglement-assisted communication method represents a breakthrough for quantum cybersecurity applications such as long-distance Quantum Key Distribution (QKD), future quantum networks, and the envisioned quantum internet. The demonstration aligns with India's national goals of developing cutting-edge quantum technologies. 

 

The project, titled ‘Design and Development of Photonic Technologies for Free Space QKD’, is supported by the Directorate of Futuristic Technology Management (DFTM), DRDO. The demonstration was led by Prof Bhaskar Kanseri’s research team and witnessed by senior dignitaries, including the DRDO DG (MED, COS & CS), Director SAG, Director DFTM, Dean (R&D) IIT Delhi, Director (DIA-CoE), and scientists from DRDO labs. 

 

Quantum entanglement-based QKD offers key advantages over traditional prepare-and-measure techniques, significantly enhancing both security and resilience. Even when devices are compromised or imperfect, the security of the key remains intact due to the intrinsic properties of entanglement. Any unauthorised interception attempts disturb the quantum state, making detection possible. 

 

Quantum communication technology offers unbreakable encryption, making it a strategic asset for securing communications in critical areas such as defence, banking, telecommunications, and national security. Free-space QKD also removes the dependence on physical optical fibre networks, which can be cost-prohibitive or difficult to install in urban or rugged terrains. 

 

Previously, in 2022, DRDO and Prof Bhaskar’s team demonstrated India’s first intercity quantum communication link between Vindhyachal and Prayagraj using underground dark fibre. In 2024, they further advanced this field by distributing quantum keys over a 100 km spool of telecom-grade fibre in another DRDO-backed initiative. 

These developments are part of DRDO’s DIA-CoE initiative, which has established 15 Centres of Excellence at leading academic institutions such as IITs, IISc, and top universities to drive innovation in advanced defence technologies.