Science & TechnologyImportant2025-06-16

India's First Free-Space Quantum Communication Trial

Why focus: GS3 Sci-Tech — Tests quantum entanglement and QKD fundamentals. Classic tech proxy setup for 'Assertion-Reason' questions.

In News

What Happened

On June 16, 2025, the Defence Research and Development Organisation (DRDO) and IIT Delhi successfully demonstrated India's first free-space quantum secure communication over a distance exceeding 1 km. The experiment, conducted on the IIT Delhi campus, utilized quantum entanglement to achieve a highly secure key rate of 240 bits per second with a quantum bit error rate below 7 percent. This was a joint effort led by Prof. Bhaskar Kanseri's team under the DRDO-Industry-Academia Centre of Excellence (DIA-CoE).

Why It Matters

This milestone marks India's entry into the era of quantum-secure communications without the need for expensive, disruptive underground optical fiber infrastructure. It enables fundamentally unhackable encryption for tactical networks, providing immense strategic value for defense, finance, and telecommunications in challenging mountainous or urban terrains.

Background

History & Context

This breakthrough builds on India's broader quantum ambitions formalized by the Union Cabinet's approval of the National Quantum Mission (NQM) on April 19, 2023, with a budget of Rs 6003 crore. Prior to this, in 2022, DRDO and IIT Delhi demonstrated India's first intercity quantum communication link between Vindhyachal and Prayagraj, but that relied on commercial underground optical fiber. In 2024, the same team successfully distributed quantum keys over a 100-km spool of telecom-grade fiber, leading up to this free-space achievement.

What Changed

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BEFORE: Secure quantum communication in India relied entirely on laying commercial underground dark optical fibers. NOW: Free-space Quantum Key Distribution (QKD) bypasses physical cables, transmitting entangled photons through the open air over distances exceeding 1 km.
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BEFORE: Extending secure military and strategic communication networks in mountainous or dense urban terrains was highly disruptive, expensive, and limited by infrastructure. NOW: Free-space optical links can be deployed flexibly in difficult terrains, establishing the foundation for future satellite-based quantum internet.
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BEFORE: Classical encryption methods used mathematical complexity, which could potentially be cracked by advanced supercomputers or future quantum computers. NOW: Quantum entanglement ensures device-independent security, where any interception attempt instantly alters the photon state and alerts the authorized users.

Prelims Angle

NCERT Connection

The concept relates directly to the Class 12 Physics NCERT textbook chapter on 'Communication Systems', which covers optical communication and the transmission of signals. The experiment utilizes principles of 'Dual Nature of Radiation and Matter' (Class 12) where photons represent individual quanta of light. In this advanced application, quantum entanglement is used for secure cryptography rather than traditional amplitude or frequency modulation.

Practice Questions

Q1

With Reference To

With reference to the National Quantum Mission and recent free-space quantum communication trials in India, consider the following statements: 1. Free-space Quantum Key Distribution (QKD) requires the installation of specialized underground dark optical fibers to maintain the entangled state of photons. 2. The National Quantum Mission was approved by the Union Cabinet in 2023 with the objective of developing intermediate-scale quantum computers and satellite-based secure quantum communications. 3. In quantum entanglement-based communication, any attempt by an eavesdropper to measure the photons instantly alters their quantum state, alerting the users. Which of the statements given above is/are correct?

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