Quantum Leap

Not the slightly peculiar late 80s science-fiction series (apologies to younger readers), but the development of workable quantum computers. Niels Bohr, the great atomic physicist, once stated that any person who on first hearing about quantum theory wasn’t completely outraged by it simply hadn’t understood it, and the same applies to quantum computing.

Most people are familiar with the Schr√∂dinger’s cat concept, i.e. that at a quantum level subatomic particles have the capability to simultaneously exist in a number of states, e.g., both a particle and a wave form. Quantum computing exploits this property to accelerate computing functions to a level far beyond anything yet seen.

Standard computers employ binary technology in which one piece of information is represented by a bit; a bit can either be a zero or one. In quantum computing, the standard unit of information is a qubit (short for “quantum bit”): this also exists in two states, but with the additional advantage of existing in a multiplicity of positions – effectively it can be both a zero and a one at the same time. Imagine the classical model of an atom, with a nucleus at its centre and electrons revolving around it (actually atoms look nothing like that, but we won’t let that detain us for now). Now we can picture a binary system as having zero at one pole and one at another, remaining in a fixed position; however, electrons have the capacity to fill any space around the nucleus, moving between positions without any intervening travel, offering an almost infinitely expanded number of points at which information could be stored.

All well and good, you may say, but is there really a need for faster computers? The answer is, of course, on a domestic/business level, not really. With the most basic mobile device containing more processing power than existed in the computers designed to operate the moon landings, and conventional processing still developing exponentially, ordinary users simply don’t need quantum computing at present. However, quantum computers could undertake specialist tasks that are far beyond the scope of today’s machines. 

One area in which they could specialize would be the swift discovery of huge prime numbers; as prime numbers are the basis of much computer encryption, a working quantum computer would be able to swiftly crack most current computer encryption. Obviously, this is highly concerning; the plus side would be that the same capacity could be used for developing almost unbreakable information security using the same techniques. Scientists are also excited by the potential of quantum computing in modeling complex chemical reactions, allowing for experimentation that could potentially develop everything from cures for cancer to perfect modelling of future climate change to the creation of novel non-polluting energy sources.

So, how far are we from this Holy Grail? The answer is that it is still some way off: Google, IBM and other companies have been locked in a battle for “quantum supremacy” for some time now, with both companies producing 50 qubit systems by 2017. However, these have no practical viability: IBM’s 50 qubit computer could sustain a quantum microstate for just  90 microseconds, which is useful as proof of concept but has little real-world value. Nevertheless, there is no reason to suppose that Moore’s Law (which predicts that processing power for conventional computers will double every two years) isn’t applicable to quantum computing, and the expert consensus seems to be that practical, workable quantum computers will be with us within a decade.

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