Scientists identify Ladakh's astronomical observatory as prime site for quantum communication

Bengaluru: Researchers from Bengaluru's Raman Research Institute (RRI) have identified the Indian Astronomical Observatory (IAO) in Hanle, Ladakh, as a top candidate for beaming quantum-based communication signals into space.

The study focuses on Quantum-Key Distribution (QKD), a cutting-edge technology in quantum communication that ensures data security through the principles of quantum mechanics rather than traditional mathematical cryptography.

In QKD, a key — a string of numbers or letters — is exchanged between two parties to encrypt and decrypt information. Unlike classical key distribution, QKD leverages quantum physics to achieve higher security. The technology finds applications in sectors such as banking, defence, and healthcare, where data protection is crucial.

Why quantum signals are secure

Prof Urbasi Sinha, head of RRI's Quantum Information and Computing (QuIC) Laboratory, explained the unique security advantage of QKD. “Quantum measurements are invasive. If a third party tries to intercept a quantum signal, the act of interception disturbs the signal, revealing the presence of an eavesdropper,” she said.

While classical satellite communication operates in megahertz (MHz) or gigahertz (GHz) frequencies, quantum communication functions in the terahertz (THz) range.

Study highlights

The research, led by Sinha and Satya Ranjan Behara, evaluated three sites for quantum signal transmission: Mount Abu, Rajasthan; Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital; Indian Astronomical Observatory (IAO), Hanle, Ladakh.

By analysing meteorological parameters like temperature, humidity, atmospheric pressure, and wind speeds, the researchers simulated signal transmission conditions.

"The atmosphere contains dust particles, gases, and water vapor, and physical processes like turbulence and rain can cause signal loss,” Sinha explained.

Their findings showed that IAO’s dry and cold conditions, low atmospheric pressure, and minimal water vapour and oxygen concentrations result in the least signal loss, making it an optimal location for quantum communication.