Quantum Communication Breakthrough in India

Summary of Quantum Communication Development by IIT-Delhi and DRDO

On June 16, 2025, the Ministry of Defence of India announced a significant advancement in quantum communication, achieved by scientists from IIT-Delhi in collaboration with the Defence Research and Development Organisation (DRDO). This breakthrough has profound implications for quantum cybersecurity.

• Quantum Entanglement: The research relies on the principle of quantum entanglement, where pairs of photons (particles of light) are generated in such a manner that measuring one photon instantaneously affects its entangled partner, regardless of the distance separating them. This phenomenon is distinct to quantum physics and cannot be explained by classical physics.

• Quantum Communication: Defined broadly, it encompasses various methods using quantum principles, particularly entanglement, to create secure communication channels impervious to eavesdroppers. If a third party attempts to intercept the communication, it disrupts the entangled state, signaling an intrusion.

• Quantum Key Distribution (QKD): A critical technique within quantum communication that facilitates secure key exchange between parties. QKD can be analogized to sending letters through a mail system where only the intended recipient has the key to the letterbox. In QKD, identical secret keys are shared between two parties, allowing secure messaging via classical encryption methods.

• Types of QKD: Two fundamental approaches to QKD are:

  1. Prepare-and-measure: One party prepares photons, and the other measures them.
  2. Entanglement-based: Entangled photon pairs are distributed between two parties, allowing for secure key generation.

• Recent Demonstration: The IIT-Delhi team, led by Prof. Bhaskeri Kanseri, successfully transmitted quantum keys over a distance of 1 km using the entanglement-based QKD methodology. This represents a progression from earlier efforts that required optical fibers. The demonstration achieved a secure key rate of nearly 240 bits per second with a quantum bit error rate of less than 7%.

• Historical Context: Earlier in 2022, the same research team had established a quantum communication link between Vindhyachal and Prayagraj, eventually increasing the distance to 380 km in 2023, and further extending to over 100 km in optical fiber links.

• Government and Strategic Implications: This development aligns with India’s National Quantum Mission, inaugurated in 2023 with a financial commitment of Rs 6,000 crore aimed at advancing quantum technologies. Defence Minister Rajnath Singh emphasized the strategic transformation in secure communications and warfare that this technology heralds for India.

• Global Context: China's establishment of the world's first quantum network covering 4,600 km with two ground-to-satellite links illustrates the competitive landscape in quantum communications. The anticipated evolution of a 'quantum internet' in the U.S. by the mid-2030s hints at extensive civilian applications including banking and telecommunications.

• Future Outlook: Advancements in quantum communication can potentially enable applications in distributed quantum computing, ultra-precise sensory technologies, and secure time synchronization across a global network, emphasizing the necessity for continued research and investment in quantum technologies.

Overall, India's developments in quantum communication signify a pivotal shift towards more secure communication paradigms, with both defence and civilian applications that will shape future technological landscapes.

Key Highlights:

• Quantum entanglement enables secure communications by revealing interceptions.
• QKD allows secure key exchange for encrypted messages.
• IIT-Delhi achieved 1 km transmission distance via entanglement-based QKD.
• Secure keying rate: 240 bits/second, with quantum error rate <7%.
• National Quantum Mission launched in 2023 with a budget of Rs 6,000 crore.
• Competitive advances noted globally, particularly China's quantum network.
• Potential for widespread applications in various sectors including defence and telecommunications.