India is moving closer to building highly secure communication networks from space after a 5.56-km quantum communication link was successfully demonstrated between BISAG-N and IIT Gandhinagar. The trial, conducted by QNu Labs, BISAG-N and IIT Gandhinagar, comes as ISRO prepares to demonstrate quantum communication from space, potentially opening the way for a new generation of secure networks for government, defence, banking and other critical services.
The technology, known as Quantum Key Distribution (QKD), uses the behaviour of light particles to securely generate and share digital keys used to protect sensitive information. If an attempt is made to intercept the quantum signals, they are disturbed, allowing the sender and receiver to detect a possible breach.
In the latest trial, quantum signals were transmitted through open air over 5.56 km. The system recorded an error rate of below 5% and generated secure keys at around 230-260 bits per second. The experiment also demonstrated accurate optical beam alignment between the two locations, a crucial capability for future satellite-based systems that will need to track ground stations while moving hundreds of kilometres above Earth.
ISRO is preparing its Quantum Technology Demonstration in Space (QuTDS) payload, with the eventual goal of establishing secure quantum links between satellites and ground stations. Satellite-based quantum communication could overcome the distance limitations of fibre networks, where quantum signals weaken over long distances, enabling secure connections between faraway cities.
Dr N Sivasubramanian, former Senior Scientist and Chief General Manager of ISRO, said quantum-secure communication would be vital for India’s future data-sharing needs. He said he had urged ISRO three years ago to establish a national quantum communication network, similar to systems being developed in Japan and China. He said the technology could securely transfer large volumes of data, including terabyte-sized files, and protect sensitive banking, defence and space-related information. He suggested initial land-based trials between SDSC-SHAR in Sriharikota and TERLS in Thiruvananthapuram before moving to satellite links, and expects the technology to become operational in India within five years.
India is also pursuing the technology under the National Quantum Mission (NQM), approved in April 2023 with an outlay of Rs. 6,003.65 crore for 2023-24 to 2030-31.