Quantum computing: What is it?

In the 1980s and 1990s, science fiction movies were obsessed with super computers and the way they would change the world. These days, super computers are relatively common, so instead we hear about “quantum computers”.

Back in 2015, IBM announced that they had managed to turn theory into reality as they unveiled their first working quantum computer. For IT geeks the news was very exciting – but what does it mean for home computer users?

What is a quantum computer?

Before trying to explain quantum computers, it helps to understand how a traditional computer – like your PC or Mac – handles information. Known as “classical” computers, these devices use long strings of “bits” to represent data. A bit can have one of two values: 0 or 1.

Everything on your computer – documents, pictures, emails and videos – are made up of very long strings of 1s and 0s. On a traditional computer hard drive, the bits are made by altering the polarity of tiny magnetic particles on the disk.

A quantum computer is very different. Instead of using bits, they use “qubits”. Qubits are stored by altering the behaviour of tiny particles like electrons or photons. More importantly, qubits are capable of representing more than just a 1 or a 0 – instead they can store 0, 1 or a “superposition” of many different numbers at once.

Using qubits, it becomes possible to carry out a “arbitrary reversible classical computation” on all those numbers simultaneously; a classical computer can only complete one calculation at a time. As a result, quantum computers are (in theory) much faster at completing complex calculations than even the fastest super computer.

If that sounds complicated, that’s because it is. Explaining a quantum computer is extremely difficult because they rely on advanced physics to carry out complex calculations. Even quantum physicists struggle to properly explain how quantum computers work.

Why do quantum computers matter?

The amount of data being created every day is phenomenal – and current computers will not be able to keep pace for much longer. Modern super computers are still too slow to perform some of the most important scientific tasks like testing the effects of new medicines at the molecular level.

With the ability to perform very complicated calculations more quickly, or to even model those drugs at the molecular level, quantum computers provide a much needed performance boost. Most data scientists agree that quantum computers are our best chance to deal with the challenges of the 21^st Century.

Will you ever own a quantum computer?

Because of their complexity, quantum computers are extremely expensive. If the technology proves to be valuable, we should see that cost fall as more computer manufacturers get on board.

The reality is that the average home user won’t need the power provided by quantum computing. Or be able to afford the electricity bill for running a device that manipulates photons and electrons to store and manipulate data!