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Quantum entanglement IIT Delhi experiment achieved a 1 km free‑space secure link with ~240 bps key rate and <7% QBER, paving the way for quantum‑safe networks under India’s National Quantum Mission.
Table of Contents
Quantum entanglement IIT Delhi: the headline milestone
IIT Delhi, in collaboration with DRDO, demonstrated entanglement‑assisted free‑space quantum secure communication over more than 1 km on campus, achieving a secure key rate around 240 bits per second with a quantum bit error rate under 7%. This real‑world test shows that quantum‑secure links can work outside tightly controlled labs, moving India closer to deployable quantum networks for critical communications.
What is quantum entanglement and why it sounds like “teleportation”
Quantum entanglement links two particles so that measuring one instantaneously determines the state of the other, no matter how far apart they are, which is why headlines sometimes compare it to “teleportation” or wormhole‑like behavior in science fiction.
In communication, entanglement enables sharing encryption keys with built‑in tamper detection, because any interception disturbs the quantum state and is immediately noticeable to the system.
How the IIT Delhi experiment worked
The team used entangled photons and a free‑space optical path between two ends of a 1 km link, then ran an entanglement‑based Quantum Key Distribution (QKD) protocol to generate shared secret keys while monitoring errors that would reveal eavesdropping.
Entanglement‑based QKD differs from prepare‑and‑measure methods by leveraging correlations from a shared entangled source, offering strong security guarantees even when devices have imperfections.
Why this matters: security, defence, finance, and beyond
Unlike classical cryptography that relies on hard math problems, quantum communication is protected by the laws of physics, making it a powerful defense against future quantum‑computer attacks on today’s encryption. Sectors like defence, banking, telecom, and critical infrastructure stand to benefit from quantum‑secure links that can flag interception attempts in real time and maintain confidentiality across challenging environments.
India’s roadmap: National Quantum Mission and satellite QKD
India’s National Quantum Mission (2023–2031) targets quantum communication, computing, and precision sensing, including satellite‑based quantum communication across 2,000+ km and multi‑node networks linking national labs and partners. Progressive demonstrations—intercity fiber links, 100+ km fiber QKD, and now 1 km free‑space entanglement—show a stepwise path toward quantum internet‑like capabilities and satellite‑assisted secure coverage.
Practical examples and everyday analogies
Think of entangled photons like a pair of perfectly synchronized coins: flip both and they always match in a way guaranteed by physics, so if anyone touches the coins mid‑air, the pattern breaks and the system notices immediately, which is how eavesdropping is exposed.
Free‑space QKD is like sending a secure light beam through the air instead of laying expensive cables, which helps in mountainous regions, dense cities, or rapid‑deployment scenarios where fiber is impractical.
Key highlights at a glance
Distance: more than 1 km free‑space optical link on IIT Delhi campus.
Performance: ~240 bps secure key rate with QBER < 7%, acceptable for entanglement‑based QKD in field conditions.
Motivation: quantum‑safe networks for defence, finance, telecom, and national resilience, aligning with India’s quantum roadmap.
References:
Press Information Bureau: DRDO & IIT Delhi Quantum Communication Breakthrough
Q & A Section
What was achieved by IIT Delhi’s quantum entanglement experiment?
The team demonstrated a 1 km free-space quantum key distribution with about 240 bps secure key rate and less than 7% QBER, showing quantum-secure links are now viable outside controlled labs
Why is quantum communication more secure than classical methods?
Because any interception disturbs the quantum state of photons, instantly alerting users to possible hacks—security is protected by the laws of physics, not just complex math.
How does quantum entanglement help in encryption?
What makes free-space QKD important for India?
It enables rapid deployment, overcomes the limitations of fiber optics, and helps connect remote, urban, or mobile nodes securely—vital for defence, finance, and disaster resilience.
What are India’s next steps in quantum technology?
Scaling free-space QKD to multi-node networks, linking labs and satellites for quantum-secure national communications as outlined in the National Quantum Mission.
