DRDO, IIT Delhi demonstrate free-space quantum secure communication over 1 km
Free-space Quantum Key Distribution (QKD) eliminates the need to lay optical fibers. The experiment attained a secure key rate of nearly 240 bits per second with a quantum bit error rate of less than 7%.
India’s Defence Research and Development Organisation (DRDO) and Indian Institute of Technology Delhi (IIT Delhi) have successfully demonstrated free-space quantum secure communication using quantum entanglement over a distance of more than 1 km via a free-space optical link established on the IIT Delhi campus.
The experiment attained a secure key rate of nearly 240 bits per second with a quantum bit error rate of less than 7%, according to a media release.
“This entanglement-assisted quantum secure communication paves the way for real-time applications in quantum cyber security, including long-distance Quantum Key Distribution (QKD), the development of quantum networks, and the future quantum internet,” India’s Ministry of Defence (MoD) said in a media release. “These efforts align with India’s broader objectives to advance quantum technologies for national development.”
Under the project ‘Design and development of photonic technologies for free space QKD’, sanctioned by the Directorate of Futuristic Technology Management (DFTM), DRDO, the demonstration was carried out by Prof Bhaskar Kanseri’s research group.
Quantum entanglement-based QKD offers several significant advantages over the traditional prepare-and-measure method by enhancing both security and functionality. Even if devices are compromised or imperfect, the use of quantum entanglement ensures the security of key distribution. Any attempt to measure or intercept the entangled photons disturbs the quantum state, allowing authorized users to detect the presence of an eavesdropper.
Quantum communication provides fundamentally unbreakable encryption, making it a dual-use technology with applications in securing data in strategic sectors such as defence, finance, and telecommunications, as well as in protecting national security-related communications. Free-space QKD eliminates the need to lay optical fibers, which can be both disruptive and expensive, especially in challenging terrains and dense urban environments, the MoD said.
India’s first intercity quantum communication link between Vindhyachal and Prayagraj in 2022, using commercial-grade underground dark optical fiber was demonstrated by DRDO scientists along with Prof Bhaskar’s team. Last year, the team successfully distributed quantum keys using entanglement over a 100 km spool of telecom-grade optical fiber in another DRDO-supported project, according to the media release.
