Casual visitors to R Vijayaraghavan’s lab can be easily dazzled by his fancy equipment, one of which can cool bits of matter within minutes to temperatures well below that of deep space.
His prize exhibit though is a tiny device that he has built, a proto-chip if you will, which he is developing to be part of powerful quantum computers in the future. Such a computer does not exist at the moment. Whoever builds one early will have a tool to dominate the world.
The foundation of quantum computing is a unit called the qubit, the basic unit of information in a quantum computer. Making qubits and getting them talk to each other is a hard task, because they are touchy and easily give up their quantum-ness when in contact with the outside world. Connecting them and making them work together is a harder task. Vijayaraghavan, a professor at the Tata Institute of Fundamental Research (TIFR) in Mumbai, has made a three-qubit processor where each qubit is connected to each of the other two qubits.
In terms of the number of qubits, it is trivial. Early this year, Google announced that it had a quantum processor with 72 qubits, and IBM had demonstrated a 50-qubit processor last year. But their processor architectures are different from that of the TIFR device. In the IBM-Google approach, a qubit is connected only to the neighbouring qubits. In the TIFR device, every qubit will be connected to every other qubit. If Vijayaraghavan manages to scale his processor to more qubits, he may have a processor that is very efficient in translating algorithms.
Quantum computers are entirely different from the so-called classical machines, as they are capable of solving problems that are impossible for today’s computers. In this sense, they are not super versions of today’s computers.
A supercomputer, no matter how fast, cannot break security codes used in military and business communications. A quantum computer can break them in minutes. If, for example, someone in the world develops a quantum computer, all of today’s security codes become worthless. We would then need to design new ones using quantum computers.
In the global race to build quantum computers, India has so far been present only in theory compared to US, China and the handful of other European countries that were spending large amounts of money. India had no national programme. It had a number of theorists, but only a few had been trying to build a quantum computing device.
A few experimental research groups started emerging about five years ago, and some of them have made progress. Now the Department of Science and Technology (DST) wants to give them more money, as it realised that quantum computers are essential to tackle problems that will develop in the future.
For the last one year, DST has been working on a national plan to fund quantum computing research. Now, it has shortlisted 53 proposals, out of which several are proposing to develop materials and build quantum devices. “We may have funded some proposals in the past,” says DST secretary Ashutosh Sharma, “but we were not focused at all.”
A well-funded national programme will try to lay a foundation for quantum computing technologies. DST is expecting to launch the programme this financial year.
When taken together, these research groups function as a national programme of sorts that represents key areas of quantum computing. One is what Vijayaraghavan and his colleagues use: the superconducting approach that creates qubits by cooling superconductors to ultra-low temperatures. Superconducting quantum chips are indeed a hot area of research, but scientists have other approaches.
State Of Property
The basic need of a computer is a property with two states, like the presence or absence of current in a transistor in contemporary computers. Vijayaraghavan uses the presence or absence of an oscillation in a device kept at low temperature.
Some physicists have tried to use spin, the way a particle aligns itself to a magnetic field, as a qubit. At the Indian Institute of Science Education and Research (IISER) in Mohali, Kavita Dorai is using spin as a quantum state, and has run quantum algorithms on a five-qubit device.
At IISER Pune, Umakant Rapol researches how to network quantum processors while TS Mahesh looks at quantum information and artificial intelligence for quantum control. The Indian Institute of Science (IISc) in Bangalore has several groups that work together. For example, assistant professor Vibhor Singh is researching on ways to build quantum processors in two dimensions, instead of 3D, as a better way of scaling them.
Now, promise of increased funding gives Indian researchers an opportunity to catch up with the rest of the world. “We are late,” says Vijayaraghavan, “but not so late that we cannot make a global impact.”
The power of quantum computing comes from the seemingly bizarre nature of matter at the atomic level. Classical computers store information in two states, either 1 or 0. In the classical world, which we all see and touch, one thing can exist in only one state at a time. In the quantum world, a particle can exist in two states. Not either 1 or 0 but both. Or other states in between. All at the same time.
Due to this property called superposition, quantum computers have the ability to do an extraordinary amount of calculations simultaneously. It can factor large numbers quickly, a feature that is important for information security.
Current security systems use factors of large prime numbers as codes, but quantum computers can decode them easily. When codes can be broken easily, we need to use quantum mechanics to make other codes that cannot be broken by quantum computers. Which is why it is important to develop this technology for business and national security.
Quantum computers will also let us simulate nature at unprecedented levels. What happens really at the molecular level inside the body? Quantum computing will help simulate molecular interactions so well that we can design super-drugs that can cure diseases with little or no side-effects. “These are technologies no one is going to give you,” says Umakant Rapol, associate professor at IISER in Pune.
Among other things, Rapol is developing methods to scale quantum computers to useful levels. So far, one of the biggest problems in quantum computing is our inability to put together a large number of qubits to form a working computing device. For some reason, the qubits do seem to lose their quantum behaviour when they are put together.
None of this research is going to result in a commercial quantum computer in the country soon. But developing the technology can have other uses, many of which are strategic. For example, quantum computers are supposed to let us develop extremely sensitive interferometers that can provide precise locations of objects, which, in turn, can be useful to anything from leaking pipes to forecasting volcanic eruptions.
In the end, a large number of strategic industries are going to be based on quantum computing and related sciences. “In the 21st century,” says Kavita Dorai, “there is a clear advantage for nations having information. To use this information, we have to invest in quantum information and related technologies.”
India is now taking small steps towards laying the foundations of this technology. “Money may induce those who are working in the periphery to move into this area,” says Ashutosh Sharma.