Quantum computing uses quantum bits, or qubits. A conventional bit is based on an electrical current being switched on or off, which enables binary calculations. A qubit can be both on and off at the same time. This allows a quantum computer to perform far more calculations with far fewer qubits. In theory, a quantum computer could deliver accurate meteorological projections, perform seismic data analysis, analyse protein folding, etc. These tasks involve computations so complex that even supercomputers cannot handle them. But quantum computers are also prone to far higher levels of error. Superpositions (where a qubit is both on and off) can collapse quickly. The software programming is different, and requires excellent error control and management. Researchers have found it hard to maintain physically stable configurations. The largest known quantum computer has a capacity of just 433 qubits. Moreover, they are huge installations which must be housed in super-cold, seismically stable places since even passing trucks can cause errors through imperceptible tremors. Special materials and rare helium isotopes are used to manage cooling and shielding, quite apart from specialised semiconductors allowing for quantum logic gates.
Quantum applications in the related fields of communications and cryptography depend on another quantum property — “entanglement”. If two particles are entangled, a change in the state of one particle leads to instantaneous change in that of the paired particle. This occurs even if the particles are separated by a distance. Cryptographically secure communications can be generated by separating two entangled particles. If a message is intercepted, the interference changes the state of the entangled particles. Moreover, by sharing entangled particles as keys, communications become unbreakable, even if messages are intercepted. The Indian Space Research Organisation has already demonstrated proof of concept in quantum key distribution, and secure quantum communications at short distances. Scaling up to doing it at greater distances should be possible.
At the same time, quantum computers could potentially break most current encryption, by quickly solving the mathematical problems on which modern cryptography is based. The NQM mission will also develop magnetometers with high sensitivity, and atomic clocks to enable precision timing, communications, and navigation. Building all this, and using it well, will need extensive research into the design and synthesis of superconductors, novel semiconductor structures, and materials with complex topological structures as well as developing new software. The research in itself will have enormous spin-offs, by greatly improving India’s grasp of multiple material sciences and technologies. The stated mission thus can also lead to benefits across fields as diverse as communications, health, financial sector, energy management, drug design, as well as aerospace and military applications.
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