On June 16, 2025, a joint effort by the Defence Research and Development Organisation (DRDO) and the Indian Institute of Technology Delhi (IIT-Delhi) culminated in a groundbreaking demonstration of quantum communication through free space over more than a kilometre. The experiment, conducted on the IIT-Delhi campus, successfully employed quantum entanglement to securely transmit cryptographic information without relying on traditional optical fibre cables. This success signals a shift from conventional fibre-based systems toward free-space methods that are essential for developing quantum networks across remote regions—and even space—through satellite-based technologies.

Quantum communication represents a dramatic transformation in how secure data can be transmitted. Unlike traditional cryptographic techniques, which depend on the difficulty of solving complex mathematical problems, quantum systems leverage the fundamental laws of physics—specifically, quantum mechanics—for data protection. A key feature is the use of entangled photons: when one particle’s state is measured, its partner instantly reflects that change, even across vast distances. This property, combined with the inability to copy unknown quantum states (the no-cloning theorem), makes eavesdropping nearly impossible. Attempts to intercept quantum data inherently disrupt the communication, alerting users to potential intrusions.

The free-space quantum communication trial conducted by IIT-Delhi used entanglement-based Quantum Key Distribution (QKD) to generate secure encryption keys. Despite free-space setups being prone to environmental interference—such as atmospheric disturbances and background light—the team managed to achieve a secure key rate of 240 bits per second and kept the quantum bit error rate under 7%, well below the 11% threshold for secure operation. This proves the feasibility of deploying the technology in real-world settings, including remote or conflict-prone areas, without needing extensive physical infrastructure like buried fibre optics. With national security, economic resilience, and advanced communication networks at stake, India’s continued progress in this field positions it as a rising global power in the quantum technology race. 

Disclaimer: This image is taken from ANI.