What's Next? by Jim Al-Khalili

Author:Jim Al-Khalili
Language: eng
Format: epub
Publisher: Profile
Published: 2017-03-17T04:00:00+00:00

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Quantum computing

Winfried K. Hensinger

When I grew up in the early 1980s, conventional computers had only recently become commonplace. In fact, I learned my typewriting skills on a mechanical typewriter, and life in general was quite different – no electronic ticket machines at train stations, no internet, no smartphones. In fact, common tasks did not rely on the existence of computers and many things we take for granted today simply did not exist. Conventional computers today have an impact on nearly all aspects of our lives and we cannot imagine a life without them. Scientists and politicians have coined a term for a technology that changes all of our lives: they call it ‘disruptive’. The term is used because of the potential of a technology to transform our lives in a step-changing, abrupt and overarching way. In the next ten to twenty years, I believe, we will see the emergence of another disruptive technology – quantum computing.

Let’s be clear about something first: quantum computers are not simply very fast computers. In fact, they have very little to do with conventional computers, and it is unlikely they will be used to tackle tasks for which we currently use conventional computers. In contrast, quantum computers may enable us to solve certain problems that we never even thought could be solved: a class of problems that might take even the fastest supercomputer billions of years to crack. Quantum computers will likely provide us with entirely new capabilities, and as such change our lives in very unexpected ways. To appreciate some of these capabilities, and to imagine the ways in which they will change our lives, it is best to start at the beginning and to describe what the working principle of a quantum computer actually is. In order to give you an idea, let me start, if I may, with a small introduction to quantum physics.

In short, quantum physics is a theory that explains the world around us. However, it is a rather strange theory. For a start it predicts that something can be at two different places at the same time. Yes, you heard that right: quantum physics, in principle, allows me to sit on my desk in Brighton to write this chapter while simultaneously going for a swim on a beach in Florida. Unfortunately, this does not happen with very large objects such as people (I certainly wish right now that it did). However, it is quite regularly observed in the laboratory when studying the behaviour of individual atoms. Indeed, an atom can be at two separate locations at once. This phenomenon is referred to as ‘superposition’. Physicists have been stunned by this strange prediction of quantum physics and have carried out numerous experiments trying to disprove it. However, experiment after experiment has shown that this can and does indeed happen.

Let me tell you about an example of quantum weirdness from my own scientific career. A quantum physicist by the name of Gerard Milburn had predicted that it should be possible to make an atom move forward and backward simultaneously.

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