India’s computing prowess is set for a quantum leap

The NQM aims to build “quantum computers with 50-1,000 physical qubits in eight years". It also looks to develop satellite-based secure communications between ground stations over 2,000 km apart, inter-city quantum key distribution over 2,000 km, and a multi-node quantum network. The NQM will also make magnetometers with high sensitivity, and atomic clocks.

All these domains require cutting-edge R&D, and have a steep learning curve. Even if all the targets are not realised, the NQM’s efforts should boost India’s grasp of quantum computing and the associated material sciences.

Q-computing uses several peculiar properties of subatomic particles. A conventional computer works via currents passing through switches. At a given moment, each computing unit or bit is either at zero (current off) or one (current on). Quantum bits, or qubits, can be in a third state of “superposition" – both on and off at the same time.

Because of this, qubits can store much more information, and crunch numbers much faster. A two-bit system may represent any of four states (00, 01, 10, and 11) but can only represent one at a given time. A two-qubit system on the other hand can represent all four states at the same time.  Qubit processing power and storage thus grows exponentially – 64 qubits can represent a million terabytes (10 followed by 18 zeros).

Because of this, quantum computers could be millions or billions of times faster than conventional supercomputers. This could allow them to accurately model weather and climate, understand protein-folding (which is critical to understanding disease and drug discovery), map DNA encoding, map urban traffic in real time, and crack current encryption.

While Q-computers could break current encryption with sheer speed, other quantum properties could be used to develop new standards of unbreakable encryption. Subatomic particles can be paired, or “entangled". If the state of one entangled particle changes, the state of the paired particle also changes instantaneously, even if they are physically separated. Moreover, the state of any particle changes the instant it is observed and measured, since it is sensitive to the energy used to observe it.

By entanglement, encryption keys can be created and shared. If an entangled communication is intercepted, the sender and recipient will both be aware of it and the message will become impossible to decrypt. ISRO demonstrated in 2022 that it can use entanglement to share keys and develop encrypted quantum communications.

Given all the promise, India is doing well to allocate resources to long-term R&D in this space. So where do the problems lie? The stated NQM targets are considered optimistic by most experts, due to the significant engineering problems that need to be solved.

India is the seventh nation to announce a quantum mission – China and the US in particular have poured money into it for over a decade. Corporate giants such as IGM, Google and Microsoft and a host of universities and research labs have also invested a lot in quantum R&D.

The largest Q-computer is believed to be IBM’s Osprey, which has a 433-qubit capacity. Scaling up to 1,000 qubits is a tall order. The proof of concept of quantum communications has also been demonstrated in many labs (including ISRO’s Ahmedabad facility), but only at close distances. Scaling up wirelessly across 2,000 km, as announced by the NQM, or connecting stations on the ground with satellites will be a challenge (satellite orbits are anywhere from 400 km to 36,000 km above Earth’s surface).   

Quantum computers also operate at -196 to -200 degrees Celsius, and even passing data through their circuits can generate enough heat to cause problems. They need to be shielded from mild tremors caused by vehicular traffic or construction. The circuits and cooling systems are made of special materials and use rare helium isotopes. The software has to be built differently to handle quantum superpositions.

Building all this will require R&D on the design of superconductors, new types of semiconductor structures, and new types of materials, apart from research into software development. Assuming the R&D is well-directed, there will be a lot of learning involved. Whether NQM achieves its targets or not, India will take a big leap forward in terms of technological capacity simply by doing this research.

However, another note of caution is in order. A consistent and robust approach to making strides in science, technology, engineering, and mathematics (STEM) cannot involve expunging from school textbooks basic science like the theory of evolution, as is being done.