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Quantum of solace

Ever since computers were developed, they have been getting smaller and smaller. Now it is time for them to take a quantum leap, says Aswin Sekhar

Researchers at Princeton University in the US have taken a giant step towards building a quantum computer with easily available materials. The team has come up with a key piece of hardware made of silicon - the material used in conventional computers and smartphones - that is capable of very precisely controlling quantum behaviour between two electrons. Although other companies and research groups have put together quantum computers, those systems use exotic materials such as superconductors or charged atoms held in place by lasers.

The conventional computer works on the binary values of 1 or 0 - representing on or off in electronics and true or false in logical mathematical operations. The bits at the heart of a quantum computer, meanwhile, are qubits (quantum bits), which can simultaneously be a 1, 0, both or anything in-between. If a binary system has a 1 or 0 at opposite poles of a sphere, then a quantum one has values anywhere and everywhere. This allows a quantum system to calculate really fast because it can test every possibility simultaneously; no need to wait for one calculation to finish before beginning another. There is, of course, a caveat: you have to control the qubits and the subatomic particles in which they are stored. And that is very, very difficult.

"The biggest challenge in building a practical quantum computer is decoherence, which means unwanted interaction between the quantum computer and its external environment. Over the last 20 years, physicists and engineers have made incredible progress in reducing decoherence. It's only within the last few years that qubits have performed well enough in isolation so that one can integrate dozens of them and seriously expect to see a speed up over a classical computer," says Scott Aaronson, a noted theoretical computer scientist based at the University of Texas in Austin, US.

The quantum computers that exist have to be kept at exceedingly low temperatures and away from all sorts of electromagnetic disturbances. This is pretty difficult in households that are growing increasingly "smart". It is, however, possible to maintain such stringent standards in huge data storehouses. So computing of the future will pick up data from all sorts of smart devices that are a part of the Internet of Things (IoT) and then process it at these data centres. The IoT chips will run on less and less power while the gigantic data centres will need more and more.

"Quantum computers will revolutionise technology not just in terms of the speed of computation but also in terms of the security of encrypted messages," says Vlatko Vedral, a renowned quantum information theory physicist, based at the University of Oxford in England. The rapid increase of computing speed can drastically step up the efficiency of super computing clusters used for research tasks in basic sciences and engineering. A quantum computer can solve problems that not even a conventional supercomputer can. More importantly, it could help researchers understand the physical properties of extremely small particles such as atoms and molecules, leading to major advances in materials science and drug discovery.

How will quantum computing change the world as we know it? Well, for a start, we can bid goodbye to the current forms of encryption technology.

"If and when we get full, scalable, universal quantum computers, an algorithm discovered by Peter Shor in 1994 means that such computers could be used to break virtually all of the public-key encryption currently used to secure the Internet. However, it's worth mentioning that there are other public-key cryptosystems [that is, encryption systems], most notably lattice-based ones, which are not widely used today, but which we won't know how to break even with a quantum computer," says Aaronson.

Fortunately, quantum computing will also bring along a solution to the encryption problem. "Luckily, quantum encryption is readily available and offers a higher degree of security. A quantum cryptographic protocol is planned next year between Shanghai (Alibaba) and Singapore (Centre for Quantum Technologies) that will demonstrate the use of long-range entanglement for the purposes of communicating more securely," reveals Vedral.

Some of the most exciting possibilities of quantum computing lie in the area of public health. Researchers at the University of Glasgow are developing ultrasensitive cameras that can actually detect light down to a single photon. This has the potential to detect cancer without invasive medical imaging. In Australia, instead of using magnets to create 3D images, researchers have come up with a nano-MRI that uses the magnetic properties of the qubit to allow imaging at the molecular level, at least theoretically. If used to determine the structure of biomolecules such as proteins, it could overcome many issues researchers face when developing new drugs.

"We support the work of scientists whose contributions in quantum research are leading to transformative innovations. Thanks to their efforts, we will be able to build sensors so sensitive that they can detect a single molecule, design new drugs and medical therapies, and model new materials for renewable energy production and power transmission," says Canadian minister of science Kirsty Duncan. The Prime Minister of Canada, Justin Trudeau, was a hot topic of conversation some time ago because of his special interest in and personal knowledge of quantum computing research.

Now we know the future of computing lies in quantum physics.

The author is an Indian scientist based at CEED, University of Oslo, Norway

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