In a significant stride towards a new era of secure communications, India’s Defence Research and Development Organisation (DRDO) and the Indian Institute of Technology (IIT) Delhi have successfully demonstrated a groundbreaking quantum communication technology. The joint team showcased free-space Quantum Key Distribution (QKD) using quantum entanglement over a distance of more than one kilometer, a development that promises to render communication networks fundamentally unbreakable and is being hailed as a “game changer in future warfare” by Defence Minister Rajnath Singh.
The landmark experiment, conducted on the IIT Delhi campus, paves the way for a future of quantum-powered cybersecurity, heralding the development of advanced quantum networks and a future quantum internet. This achievement places India among a select group of nations actively developing this next-generation technology.
The Milestone Achievement
The demonstration, led by Professor Bhaskar Kanseri’s research group at the DRDO-Industry-Academia Centre of Excellence (DIA-CoE) at IIT Delhi, achieved a secure key rate of approximately 240 bits per second with a quantum bit error rate of less than 7%. This successful test of entanglement-based quantum communication is a crucial step towards real-world applications in strategic sectors like defence, finance, and telecommunications.
A key advantage of this free-space QKD technology is its independence from traditional optical fiber cables, which can be expensive and challenging to deploy in difficult terrains or dense urban landscapes. This makes the technology highly adaptable for securing military and critical infrastructure communications.
This success builds on previous achievements by the same team, including India’s first intercity quantum communication link between Vindhyachal and Prayagraj in 2022 using optical fiber, and a 100 km entanglement-based key distribution over telecom-grade fiber in 2024.
How This Quantum Stuff Works: A Simple Explanation
The technology at the heart of this breakthrough, quantum entanglement-based Quantum Key Distribution (QKD), might sound like something out of science fiction, but its core principles can be understood with a simple analogy.
What is Quantum Entanglement?
Imagine you have a pair of “magic” coins. These coins are intrinsically linked in a special way – if you flip one and it lands on heads, you instantly know the other, no matter how far away it is, will land on tails. This is the essence of quantum entanglement, a phenomenon where two or more quantum particles become linked in such a way that their fates are intertwined, regardless of the distance separating them. In the real experiment, scientists use particles of light, called photons, instead of coins.
How Does it Secure Communication?
The security of QKD comes from a fundamental rule of quantum mechanics: the very act of observing a quantum particle can change its state.
- Sharing the Secret Key: The sender and receiver (let’s call them Alice and Bob) start generating and sharing a secret key using these entangled photons. They measure certain properties of the photons they receive. Because the photons are entangled, the results of their measurements will be perfectly correlated, creating a shared, secret random sequence of ones and zeros – this is the “key.”
- Detecting an Eavesdropper: Now, imagine an eavesdropper, Eve, tries to intercept this key. If Eve tries to measure the photons being sent to Bob, her measurement will inevitably disturb their delicate quantum state. This disturbance is like leaving a footprint.
- The Giveaway: When Alice and Bob later compare a small portion of their keys, they will find mismatches that shouldn’t be there. These discrepancies are a clear signal that someone was listening in. If they detect an eavesdropper, they discard the compromised key and start over with a new one.
This process ensures that the key is only established if it’s secure. Once the secret key is safely shared, it can be used with traditional encryption methods to scramble and unscramble messages, making the communication itself virtually unhackable.
The Business and Strategic Implications
In an age of increasing cyber threats, from sophisticated hacking groups to the looming challenge of quantum computers that could break current encryption standards, QKD offers a future-proof solution. For the banking and finance sectors, this means securing financial transactions and sensitive customer data with an unprecedented level of trust. It can protect critical infrastructure, secure government databases, and provide a robust framework for the telecommunications industry to offer ultra-secure communication services to its clients.
This achievement is also foundational step towards building a “quantum internet.” Such a network would not only enable secure communication but also connect quantum computers and sensors, unlocking new possibilities in distributed quantum computing and scientific research.
India has recently been making waves in the quantum space. In April, Bengaluru-based startup QpiAI had built India’s first full-stack quantum computer. The sector is picking up pace globally — late last year, Google had released a new quantum computing chip named Willow, which was able to solve a computation in less than 5 minutes which would’ve taken leading supercomputers 10^25 years to solve, which is longer than the age of the universe. Microsoft, meanwhile, had announced that it had created a new state of matter named topoconductors, which would help create powerful quantum computers. India might still be in the early days of its quantum progress, but as recent developments show, it has already thrown its hat into the quantum ring.