Scientists from India’s Department of Space’s (DOS) Space Applications Centre (SAC) and Physical Research Laboratory (PRL), both from the city of Ahmedabad, have demonstrated quantum entanglement-based real time Quantum Key Distribution (QKD) over a 300-meter atmospheric channel along with quantum-secure text, image transmission and quantum-assisted two-way video calling, according to a statement.
The demonstration was conducted at SAC, Ahmedabad, between two buildings separated by a distance of 300 meters. The researchers conducted the experiment and demonstration several times to ensure the repeatability and robustness of the QKD system capable of providing secure keys for various applications.
The team encrypted various images using generated quantum key and transmitted over classical channel from one building to another building and decrypted at the receiving terminal in real time.
According to the statement: “This is yet another significant step towards the development of the planned Satellite Based Quantum Communication (SBQC). This feat comes after the earlier breakthrough demonstration of quantum secure videoconferencing by SAC-ISRO using ‘prepare-and-measure’ quantum communication technology, in free space, over a distance of 300 m on 19 March 2021.”
For the experiment, the scientists developed technologies such as robust & high brightness entangled photon source (EPS), BBM92 protocol implementation, NavIC enabled synchronization, polarization compensation technique etc. A cryptographic application software suite with integrated quantum security was also developed and demonstrated for text, image, video encryption/decryption.
The team also demonstrated the BBM92 protocol-based quantum communication link. The secure-key-rate achieved was ~1.8 kbps, with Quantum Bit Error Rate (QBER) of less than 10%. Quantum entanglement was achieved with Bell’s parameter and quantum visibility greater than 2.2 and 80% respectively.
According to the statement, the experiment paves the way for ISRO, Department of Space to explore satellite-based demonstrations of fundamental quantum mechanics experiments as well as quantum communication for future-proof data security.
Shri. S. Somanath, Chairman, ISRO / Secretary, DOS, Shri. Nilesh M Desai, Director SAC and Dr. Anil Bhardwaj, Director PRL were present during the demonstration.