DRDO-IIT Delhi Demonstrates Breakthroughs in Quantum Communications Technology

New Delhi: The DRDO Industry Academia–Centre of Excellence (DIA-CoE), in collaboration with IIT Delhi, has showcased groundbreaking advancements in quantum communication technologies, cementing India’s position at the forefront of this cutting-edge field. In a series of demonstrations held in New Delhi, the center unveiled its development of entanglement-based quantum key distribution (QKD) systems designed to enhance communication security.

The first significant demonstration involved entanglement distribution and QKD over a 50 km fiber link in the laboratory, marking a major milestone in fiber-optic quantum communication. In a separate field test, an entanglement distribution and QKD over 8 km of optical fiber was successfully carried out within the IIT Delhi campus. These experiments represent important steps toward achieving secure, high-performance communication systems, leveraging the properties of quantum mechanics to protect sensitive data from cyber threats.

In an equally impressive breakthrough, researchers demonstrated free-space entanglement distribution using the BBM-92 protocol—a critical QKD method—between two tables separated by 20 meters indoors and 80 meters in open space. This experiment showcased the viability of short-range quantum communication in free-space setups, a promising avenue for secure communication in environments where fiber connections are impractical.

Further expanding the scope of quantum communications, a hybrid entanglement experiment was conducted in a free-space environment. The demonstration achieved a Quantum Bit Error Rate (QBER) of around 6% over a 10-meter distance, highlighting the potential of hybrid photon systems for robust quantum communication. Additionally, the research team explored quantum key distribution systems that support multiple independent channels driven by a single source. This development could pave the way for more flexible and efficient multi-protocol quantum communication networks.

One of the major breakthroughs of the DIA-CoE initiative is the development of an all-fiber heralded photon source with an impressive second-order correlation function (g² ~ 0.01), enabling single-photon generation at rates reaching hundreds of kHz. This innovation is essential for secure quantum communication, which requires the generation of individual photons for encryption. Furthermore, an all-fiber entangled photon source was developed with high visibility, demonstrating strong quantum entanglement with a Bell test parameter exceeding 2.6, making it suitable for protocols like BBM-92.

For free-space quantum communication, a heralded single-photon source with a heralding rate of over 4 million counts per second was demonstrated, marking a significant leap in the robustness of free-space quantum communications.

These advancements build on previous milestones, including India’s first QKD demonstration between Prayagraj and Vindhyachal over a distance of 100 km in February 2022. Following this success, DRDO and IIT Delhi have intensified their collaborative efforts to advance quantum communication technologies. Notably, the indigenization of various components, such as quantum sources, detectors, and non-linear crystals, is underway. These projects are supported by the Directorate of Futuristic Technology Management under its deep-tech initiatives to foster innovative defense technologies.

Quantum communication holds immense potential for enhancing security in strategic sectors like defense and finance. By providing tamper-proof communication channels, these technologies could protect sensitive information from cyber threats, thus playing a critical role in national security.

The DIA-CoE at IIT Delhi is a testament to the growing collaboration between industry and academia in driving India’s quantum communication capabilities. With a strong national footprint in QKD, the center is contributing significantly to the global push toward secure, quantum-based communication systems.