Key Details
The 27–28 September 2026 trial tested a complete route from generating encryption keys to using them in a message exchange.
Measure | Reported Result |
|---|---|
Link | 5.56 km through open air between BISAG-N and IIT Gandhinagar |
Key generation | 230–260 bits per second—the rate at which encryption keys were generated, not message-transfer speed |
Signal quality | Quantum bit error rate below 5%, indicating a relatively stable link during the test |
Message test | Successful encryption and decryption of test messages using BISAG-N’s Vedic Kavach platform |
A Light Beam Carried the Keys
Quantum key distribution (QKD) lets two locations share the secret keys used to encrypt messages. QNu Labs’ Armos device sent the quantum signals through free space—open air rather than a fibre cable. A pointing, acquisition and tracking system kept the equipment aligned across the 5.56-km path.
The reported key rate and error rate show how the link performed during this field trial. The successful message test goes a step further: it shows that keys from the link could be used by an encryption platform, not merely generated in isolation.
Software Provides a Second Form of Protection
BISAG-N’s Vedic Kavach uses post-quantum cryptography: encryption methods designed to remain secure against attacks by future quantum computers. This is different from QKD, which uses specialised hardware to distribute keys. The trial brought the two approaches together and also used quantum random number generation.
That combination is intended to keep communications protected if the open-air quantum link becomes unavailable. The release reports successful integration and message exchange, but not a separate test of how the system performed during a link outage.
Policy Relevance
The advance is a working field demonstration of an integrated system, not yet a deployable secure network. For potential users of critical communications, the next evidence needed is practical: whether the link remains available under changing conditions, whether it generates enough usable keys over time, and whether encryption continues reliably when the optical path is interrupted.
The result gives India a basis for testing longer-distance links. Satellite-based quantum communication remains a prospective application, not an outcome of this trial.
Relevant Question for Policy Stakeholders: What reliability and independent security tests should the combined system pass before it is considered for critical communications?
Follow the Full Press Release Here: India’s First 5.56-km Free-Space Quantum Key Distribution Link Demonstrated