- Why in news
- On 3 October 2026, MeitY said QNu Labs, BISAG-N and IIT Gandhinagar demonstrated India's first 5.56 km free-space QKD link, in a trial on the night of 27–28 September.
- What it is
- Quantum Key Distribution (QKD) uses quantum states of light to share encryption keys between two parties. Any eavesdropping disturbs the quantum states and shows up as errors, so it can be detected. Free-space QKD sends the photons through air or space instead of optical fibre, which is the basis for satellite-based quantum communication.
- Distance and first
- The link spans 5.56 km and is described as India's first free-space QKD link at this scale.
- Performance
- Quantum Bit Error Rate stayed below 5% and secure keys were generated at 230–260 bps.
- Two security layers
- QNu Labs' hardware QKD device Armos was combined with BISAG-N's software-based post-quantum cryptography platform Vedic Kavach, which uses quantum random number generation.
- BISAG-N
- BISAG-N is an autonomous scientific society under MeitY working in space applications, satellite communication and geo-informatics.
- Principle of QKD
- QKD security rests on the fact that measuring a quantum state disturbs it, so eavesdropping is detectable. It distributes keys, not the message itself.
Don’t confuse with QKD vs post-quantum cryptography: QKD uses quantum physics to share keys and needs special hardware. Post-quantum cryptography uses classical mathematical algorithms believed to resist quantum computers.
Don’t confuse with Free-space vs fibre QKD: Free-space QKD sends photons through air or space and can extend to satellites. Fibre QKD uses optical cables and loses signal over distance.
Science and technology: 57 Prelims questions since 2013; most test the concept behind the news, not the news itself. In Mains, 12 news-triggered questions.
Why it matters
- Strengthens India's capability in secure communication against future quantum-computer threats.
- Is a step toward longer-distance and satellite-based quantum-secure networks.
Problems
- Short range and low key rate (230–260 bps) limit practical use; free-space links are sensitive to weather and alignment.
- Scaling beyond tens of km needs satellites or trusted nodes and costly specialised hardware.
Way forward
- Move to longer links and satellite-based QKD, alongside adoption of post-quantum cryptography standards.
- Build indigenous hardware and testbeds through academia-industry partnership.
Put in your answer
India's first free-space QKD at 5.56 km: Example of indigenous quantum communication effort by QNu Labs, BISAG-N and IIT Gandhinagar.
Layered security: Combining hardware QKD with software post-quantum cryptography keeps communication secure even if the quantum channel is briefly down.
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UPSC’s own questions that come close to this issue, from our Prelims and Mains banks.
Prelims practice · Statements
Ours, not from a UPSC paper
Consider the following statements:
- 1.The first free-space Quantum Key Distribution link demonstrated in India, at a scale of 5.56 km, was set up between BISAG-N and IIT Gandhinagar.
- 2.In Quantum Key Distribution, an eavesdropper's attempt to measure the quantum states disturbs them, so the users can detect the eavesdropping.
- 3.BISAG-N, which developed the Vedic Kavach platform, is an autonomous scientific society under the Department of Space.
Which of the statements given above is/are correct?
True or false?
1 of 7
Statements the way Prelims prints them. Say first, then see the fact.
1.The demonstrated QKD link was set up between BISAG-N and IIT Gandhinagar over a free-space optical channel.
True. The channel ran between BISAG-N and IIT Gandhinagar.
2.The trial achieved a Quantum Bit Error Rate below 5%.
True. QBER was stable below 5%.
3.The keys generated were used with Vedic Kavach, a post-quantum cryptography enabled platform of BISAG-N.
True. Keys were integrated with BISAG-N's Vedic Kavach.
4.BISAG-N is an autonomous scientific society under the Department of Space.
False. BISAG-N functions under MeitY.
5.In QKD, an eavesdropper's attempt to measure the quantum states disturbs them and can be detected by the users.
True. Measurement disturbs quantum states, revealing eavesdropping.
6.QKD directly transmits the encrypted message itself through quantum states, rather than only the encryption key.
False. QKD distributes encryption keys; the message is encrypted and sent separately.
7.Post-quantum cryptography relies on quantum physics hardware to protect keys, unlike QKD, which uses mathematical algorithms.
False. It is the reverse: QKD uses quantum physics; post-quantum cryptography uses classical algorithms resistant to quantum attacks.
Written by us from the release, not by UPSC; checked by a second model.
Worth revising until Prelims 2028: most news questions come within two years of the event.