Thread by @Chethan_Dash

Scientists from SAC and PRL recently demonstrated quantum entanglement based real time Quantum Key Distribution (QKD) over 300m atmospheric channel along with quantum-secure text, image transmission and quantum-assisted two-way video calling. @isro

The demonstration was conducted at SAC between 2 buildings 300m apart. This experiment & demonstration were repeated over several nights for repeatability and robustness of indigenously developed QKD system that can seamlessly generate, utilise secure keys for various apps.

@isro: Various images were encrypted using a generated quantum key and transmitted over a classical channel from one building to another building separated by 300m and decrypted at the receiving terminal in real time.

This is a significant step towards development of planned Satellite-Based Quantum Communication (SBQC). It comes after breakthrough demo of quantum secure videoconferencing using ‘prepare-and-measure’ quantum communication tech, in free space on March 19, 2021.

In order to achieve this, scientists developed various key tech like robust & high brightness entangled photon source (EPS), BBM92 protocol implementation, NavIC enabled synchronisation, polarisation compensation technique etc.

A cryptographic application software suite with integrated quantum security has also been developed and demonstrated for text, image, video encryption/decryption.

The BBM92 protocol based quantum comm link was demonstrated in the experiment. 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%.

With these developments, @isro , DoS is getting ready for satellite based demonstrations of fundamental quantum mechanics experiments as well as quantum communication for future-proof data security.

S Somanath, chairman, Isro witnessed this live breakthrough demonstration at SAC, Ahmedabad. Nilesh M Desai, director, SAC and Anil Bhardwaj, director, PRL were also present during the demonstration.