India’s unique geographical diversity could play a critical role in transmitting quantum signals into space for more efficient satellite-based quantum communications, researchers from Bengaluru’s Raman Research Institute (RRI) said on Friday.
Through meticulous analysis, RRI scientists evaluated open-source data from three of India’s premier observatory sites. They identified the Indian Astronomical Observatory (IAO) in Hanle, located in Ladakh’s remote high-altitude desert, as the prime candidate for hosting this revolutionary technology.
Hanle, known for its dry, cold desert conditions, experiences winter temperatures plunging to minus 25 to 30 degrees Celsius. The region also benefits from low levels of atmospheric water vapour and oxygen, making it ideal for quantum communication experiments.
“Hanle offers all the natural conditions necessary for setting up a ground station and enabling long-distance quantum communication,” said Professor Urbasi Sinha, head of the Quantum Information and Computing (QuIC) lab at RRI, an autonomous institute under the Department of Science and Technology, Government of India.
Satellite-based quantum communications, including quantum key distribution (QKD), represent a promising approach to achieving global-scale quantum networks. To implement these, atmospheric simulations for both uplink and downlink communications are critical, as is identifying practical locations for ground stations.
While similar studies have been carried out in Canada, Europe, and China, India’s geographical diversity—from the towering Himalayas to coastal plains, deserts, and tropical regions—adds unique value to this research.
Traditional satellite communication typically operates at frequencies in the MHz or GHz range, whereas quantum communication functions at much higher frequencies, measured in THz. The researchers worked with signals in the 370 THz band (810 nm wavelength) as outlined in their paper published in EPJ Quantum Technology by Springer Nature.
Using open-source data on temperature, humidity, atmospheric pressure, and other meteorological parameters, researchers evaluated three observatory sites: IAO Hanle, Mt Abu in Rajasthan, and Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital, Uttarakhand.
“India’s geographical diversity offers a vast and versatile template for quantum communication research that could be applied globally. This versatility could make our research invaluable for future quantum satellite projects worldwide,” Professor Sinha added.
Proposed satellites for secure quantum communication would operate in Low Earth Orbit (LEO), with altitudes of up to 500 km. Beacon signals would be used to track moving satellites and align them with corresponding telescopes. According to co-author Satya Ranjan Behera, the team’s proposed system involves a main signal at 810 nm, with uplink and downlink signals using 532 nm and 1550 nm wavelengths, respectively.
(Inputs from IANS)