CHENNAI: India's push to build highly secure communication networks is moving closer to space, with a 5.56 km quantum communication link successfully demonstrated between BISAG-N and IIT Gandhinagar. The experiment by QNu Labs, BISAG-N and IIT Gandhinagar is significant, as reports say ISRO prepares to demonstrate quantum communication from space, potentially paving 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), is essentially a highly secure way of creating and sharing the digital "keys" used to protect sensitive information. Unlike conventional encryption, QKD uses the behaviour of tiny particles of light to detect any attempt to intercept the key.
In simple terms, if someone tries to secretly observe the quantum signals carrying the key, the signals get disturbed. The sender and receiver can detect this disturbance and know that the communication may have been compromised. This makes it particularly useful for protecting highly sensitive information.
I requested the ISRO management to establish a quantum communication network in India three years ago, similar to those being developed in countries such as Japan and ChinaDr N Sivasubramanian, former Senior Scientist and Chief General Manager of ISRO
During the latest trial, quantum signals were sent through open air over 5.56 km between BISAG-N and IIT Gandhinagar. The system recorded an error rate of less than 5%, while secure keys were generated at around 230-260 bits per second.
The trial also demonstrated the ability to keep the optical beam accurately aligned between the two locations. This is important because a similar system will have to precisely track a ground station when a satellite is moving hundreds of kilometres above the Earth.
This is where ISRO's plans become important. The space agency is preparing to demonstrate quantum communication technology through its Quantum Technology Demonstration in Space (QuTDS) payload. The eventual aim is to establish secure quantum links between satellites and ground stations.
Conventional fibre-based quantum communication becomes difficult over very long distances because the quantum signals weaken as they travel through optical fibre. Satellites could overcome this limitation and help connect distant cities through secure quantum links.
Dr N Sivasubramanian, former Senior Scientist and Chief General Manager of ISRO, told DT Next that quantum secure communication is very important for India's future data sharing requirements.
"Quantum secure communication is one of the safest ways of transferring data. I have requested the ISRO management to establish a quantum communication network in India three years ago, similar to those being developed in countries such as Japan and China," he said.
Comparing India's progress with China, he said China had conducted trials of quantum communication over long distances and was making significant progress in the technology, such as from Beijing to Paris. Japan, too, has developed an advanced quantum communication network, he added.
He said India was also working in this field through the National Quantum Mission (NQM). (The Union Cabinet approved the NQM on April 19, 2023, with a total outlay of Rs 6,003.65 crore for the period from 2023-24 to 2030-31. The mission aims to support and scale up scientific and industrial research and development and create a strong ecosystem for quantum technology)
Explaining the advantages of quantum-secure communication, Dr Sivasubramanian said it could enable the transfer of large volumes of data, including terabyte-sized files, in a secure and faster manner. Since access to the encrypted information would require a quantum key, the technology could provide a high level of security against interception and hacking.
"This technology can be particularly useful for transferring sensitive information such as banking details and data related to the defence forces, ISRO and other nationally important organisations," he said.
He also said ISRO could initially conduct long-distance quantum communication trials on land, connecting the Satish Dhawan Space Centre (SDSC-SHAR) in Sriharikota with the Thumba Equatorial Rocket Launching Station (TERLS) in Thiruvananthapuram.
"Once the land-based trials are successful, ISRO can plan to establish quantum communication through satellites," he said, adding that he expected the technology to become operational in India within the next five years.