In a day and age where information processing already occurs at a blisteringly fast pace, it’s hard to imagine that computing could get any quicker – but that is precisely what the field of quantum computing is attempting to do. By applying the principles of quantum mechanics to computer science, we may soon have a generation of supercomputers unlike anything witnessed before.
In traditional transistor-based computers, such as the one you’re using to read this article, a bit (the basic unit of digital information) has two possible values, 0 and 1. In fact, all information is represented using sequences of these two characters. Advances in computing power over the years have largely been made by making transistors – the building blocks of modern electronics – smaller. Currently, about six million of them could fit into the period at the end of this sentence. As we approach the nanoscale, however, we enter the bizarre and counterintuitive world of quantum mechanics. In the words of the physicist Richard Feynman, “If you think you understand quantum mechanics, you haven’t understood quantum mechanics.”
Quantum computing works by harnessing a principle of quantum mechanics known as superposition – which holds that any physical system can simultaneously exist in all of its possible theoretical states. This means that a qubit – the quantum equivalent of a bit – can have the value 0, 1, or both values at once. This unique property can allow computations to be performed many times faster than in a ‘traditional’ computer.
Although these concepts seem to belong solely to science fiction, the reality is that quantum computing is closer to reality than we think. Google’s recent purchase of the D-Wave Two, a 512-qubit quantum computer manufactured by D-Wave, a British Columbia-based firm, could spell the start of a new and exciting period for the field. The research being done at Google, in collaboration with NASA and the non-profit Universities Space Research Association, is still in its infancy.
The initial question surrounding D-Wave was whether or not the machine actually uses quantum computing to process data. This has still not been satisfactorily answered; although Catherine C. McGeoch, a professor in technology and society at Amherst College in Massachusetts, concluded that the machine performed its calculations at least 3,600 times faster than a conventional computer, other researchers have stated that every problem the D-Wave Two has solved can be solved faster using conventional computers. Despite the debate surrounding D-Wave, its high-speed capabilities still have great potential for research and innovation.
The search for answers is not just taking place at Google; closer to home, McGill’s Cryptography and Quantum Information lab is also working on solving these problems.
The field of cryptography is one of several fields that will be greatly affected by quantum computing. One example of the effects of quantum computing is with the RSA algorithm (named after its inventors Ron Rivest, Adi Shamir, and Leonard Adleman), a widely-used encryption algorithm that relies on the perceived difficulty of factoring large prime numbers. With current computing technology, these algorithms are almost impossible to do.
With the incredibly fast processing speed of a quantum computer, it is very likely that these prime numbers will be cracked and the RSA algorithm will break down completely. This is quite serious, as everything from our online accounts to credit card purchases rely on cryptography. However, quantum computing could also enable the design of more sophisticated encryption algorithms, using the increased computing power available. This is the job of researchers in the field of post-quantum cryptography.
Widespread commercialization of quantum computers is still a long way off, with the most optimistic estimates predicting 15 years before they go on the market. The reality is that it is likely to take a lot longer; however, if anything is certain, it is that quantum computers will bring about drastic changes in the technological world.