Hanle in Ladakh: Leading Candidate for Quantum Communication Technologies, Say Indian Scientists
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New Delhi, Dec 6 (NationPress) The diverse geography of India provides a unique advantage for transmitting quantum signals into space, which could significantly improve satellite-based quantum communications, researchers from the Raman Research Institute (RRI) in Bengaluru stated on Friday.
Through meticulous research, RRI scientists examined available open-source data on three of India’s premier observatory locations, concluding that the Indian Astronomical Observatory (IAO) in Hanle, located in the pristine heights of Ladakh, stands out as the ideal candidate for this groundbreaking technology.
This site in Hanle is characterized as a dry and cold desert, with winter temperatures dropping to minus 25 to 30 degrees Celsius. It experiences low levels of atmospheric water vapor and oxygen.
“Hanle provides all the necessary natural conditions suitable for establishing a ground station and conducting quantum communication over long distances,” stated Professor Urbasi Sinha, head of the Quantum Information and Computing (QuIC) lab at RRI, which is an autonomous institute supported by the Department of Science and Technology, Government of India.
Satellite-based quantum communications, including quantum key distribution (QKD), represent one of the most promising pathways towards global quantum communications. It is essential to perform atmospheric simulations for both uplink and downlink quantum communications to assess the practicality of potential locations.
While similar studies have been completed in regions such as Canada, Europe, and China, India's extensive geographical diversity—ranging from the Himalayas to coastal plains, deserts, and tropical areas—could render this analysis particularly significant.
While satellite communication operates within frequencies in Mega Hertz (MHz) or Giga Hertz (GHz), quantum communication functions in Tera Hertz (THz), with 100 THz being the most commonly referenced frequency, often expressed in nanometers.
In a paper published in EPJ Quantum Technology, Springer Nature, the researchers noted their work in the signal band of 370 THz (810 nm).
Authors Sinha and Satya Ranjan Behera at the QuIC lab utilized existing open-source data regarding temperature, humidity, atmospheric pressure, and other critical meteorological factors from three locations: IAO Hanle, Mt Abu in Rajasthan, and the Aryabhatta Institute of Observational Sciences (ARIES) in Nainital, Uttarakhand.
“India’s vast array of geographical terrains and diversity could potentially serve as a universal template applicable anywhere in India or globally. This adaptability could make the research invaluable for future quantum satellite initiatives worldwide,” remarked Sinha.
The proposed satellites for establishing secure satellite-based quantum communications are planned to orbit within Low Earth Orbit (LEO), at a maximum altitude of 500 km from Earth.
“Beacon signals are employed to track the moving satellite and align it with the corresponding telescope. Our primary signal will be at 810 nm while the uplink and downlink will utilize 532 nm and 1550 nm wavelengths, respectively,” explained Behera.
