Quantum computer plans unveiled

25 July 2017

Interview with

Winfried Hensinger, University of Sussex

In the Hitchhiker’s guide to the Galaxy, the supercomputer ‘Deep Thought’ was given the challenge of solving the meaning of life, the Universe and everything. The answer was, as fans will know, a rather disappointing 42. But now we may be getting closer to building such a computer ourselves. Because scientists from the University of Sussex have come up with a design for what would be the most powerful computer ever built. It’s a quantum computer and commentators say machines like it will transform the fields of medicine, e-commerce and, who knows, possibly tell us the real answer to life, the Universe and everything. Izzie Clarke met with Winfried Hensinger, who’s leading the project.

Winfried - It’s really big. Right now it fills a huge laboratory and as we build a large scale machine it will certainly fill a whole building and maybe it will fill a whole football pitch. Think of it as a masterpiece of engineering; tremendously difficult engineering.

Izzie - For one day only, a large bunker was placed in the centre of London which displayed the blueprint to building the most powerful computer on Earth. But, this isn’t a computer as we know it. Using planes and planes of microchips, scientists can use charged atoms called ions to carry out enormous calculations using the laws of quantum physics...

Winfried - Quantum physics is a very, very strange theory and has really wierd predictions. An atom can be in two different places at the same time. So you could be standing here and you could be at home having breakfast all at the same time, and that actually exists in the world of quantum physics. We train these quantum effects in order to build a very, very powerful computer which is nothing like a normal, conventional computer.

Izzie - The key to this quantum computer is that its circuit can operate by not just being on or off like a switch, but by occupying a state that is both on and off at the same time. This is down to quantum mechanics, which allow very small particles to be in different places simultaneously, where they stay in these states until they are either observed or disturbed. It’s a bit like flipping a coin. The coin is both heads and tails when it’s in the air but it’s only heads or tails once it’s caught...

Winfried - What you actually see is a very authentic model of a quantum computer as we have it in our lab at the University of Sussex, which has a vacuum better than that of outer space. Inside this vacuum system there are silicon microchips. We’ve developed a new way where you apply voltages to one of the these silicon microchips and we use these to produce electric fields, and these electric fields make individual charged atoms, or ions, that levitate above the surface. What we’ve shown is a new type of approach to quantum computing.

Izzie - It’s on these small particles that information is encoded. Our standard computers carry information in bits with values of zero or one. Quantum computers use quantum bits or qubits, where they can be both zero and one. Previously, small scale quantum computing methods used lasers to help process the calculations carried out by these qubits. However, that provided some issues when upscaling…

Winfried - Imagine you wanted to build a large scale quantum computer which would require millions or billions of qubits. Imagine you need to align millions or billions of laser beams with the accuracy of a hundredth of the width of a human hair. What we’ve done is we’ve taken away all this requirement of using all these laser beams and instead replaced them that with voltages to apply to a microchip.

Izzie - Because these qubits can be in multiple values at the same time, more information can be encoded on them. We’re talking about calculations that even the fastest supercomputer would need millions of years to calculate. For such a powerful computer you’re going to need a pretty big circuit board known as a module. It’s a large, flat microchip that contains lots of routes for the ion to move across, along with control electronics that allow this movement. Their motion actually looks like a game of Pacman. And more modules means more ions and that’s what increases the computational power...

Winfried - We’ve developed a new way to connect modules. Traditionally, people thought you’d have to use an optical fibre, so we came up with a new approach to do this. We move ions using electric field connections from one module to another and with that we are going to be able to do this 100,000 times faster than the state of the art technology around right now. And this is the second exciting breakthrough we have.

Izzie - In some aspects a quantum computer works in a similar way to a standard computer running calculations based on an input. But, thanks to quantum, both the information a quantum computer can store and it’s power is incomparable.

Imagine you were looking for someone in a public phone book. The standard process would be to go through each entry individually until you found the right person. Because these ions can take multiple states, a quantum computer would be able to search every name and number, so that’s every single possible answer, all at the same time. But what can we use these quantum computers for?

Winfried - Quantum computers can tackle problems even the fastest supercomputer would take billions of years, so it’s a whole set of opportunities. For example, creating chemical reactions like creating new pharmaceuticals. Being able to understand how to make new materials; stronger materials but lighter materials. Think about optimisations in the the stock market - very quickly, classical computers just run out of computational power. It’s more like getting a new capability that you didn’t have before...

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