Sunday Science: Quantum Computing

In a normal computer, information is stored using “bits”. A bit is either a one or a zero.

A quantum computer has “quantum bits” and — here’s the odd thing — a quantum bit can be both a one AND a zero at the same time.

This is pretty important.

If a normal computer is dealing with a complex calculation, it will go through all the different possible combinations of ones and zeros to find the answer. If it’s a REALLY complex calculation, it’s going to take a long time.

But, with a quantum computer, all the bits can be in both the one and zero state at the same time. So, you just need to do one calculation where you test all the possibilities simultaneously to get the right answer.

In other words, a quantum computer is much quicker than a normal computer.

Let’s look at a Lego example.

We need to build a car and we’ve lost the instruction manual.

​Ironman tries to solve it using a classical computing approach — he goes through every piece of Lego and tries multiple combinations of pieces until he makes the car.

He gets there in the end, but it takes ages.

Then Flash comes along. He uses a quantum computing approach.

Every piece of Lego is in the right and wrong position simultaneously. It’s like having every possible combination of Lego already at your fingertips — you don’t have to build each combination.

Instead you run one calculation to go through all these possibilities and pick the right one.

He gets there too, but it takes a fraction of the time (as you’d expect with Flash).

Is it difficult to build a quantum computer?

Yes. To build a quantum computer, you need incredibly good control over individual particles.

This is very difficult to do. If you just shove them all in one pot, the particles interact with one another and lose the information they are meant to store.

You need to be able to trap them and direct them so they can hold or change their information.

Designing this trap is one of the biggest challenges for quantum computers. The particles tend to interact with the trap and lose their information.

That said, quantum computers are now available.

Where can I buy one?

I’m afraid you can’t — they’re just available within the research community at the moment. For example, Canadian company D-Wave launched its cloud-based quantum computing service in 2010. It can only run a limited range of calculations, but several research groups have used the service.

Also, IBM announced just this week that they will roll out the world’s first commercial quantum system this year. It’s early days but it could be that start of a quantum computer market.

I bet Tony Stark will want one for Christmas.

Extra reading — and watching

Is it just me, or do scientists like the word “quantum” a lot? I’d recommend that you read my Sunday Science post on quantum mechanics if you want a little background on “the science of the very small” (which is all quantum mechanics really is).​

Wired magazine gives a great overview of quantum computing — including the challenges to making theses computers. And if you fancy something a little more in-depth, check out this article “A Tale of Two Qubits” from Arstechnica.

Canadian Prime Minister Justin Trudeau also called a reporter’s bluff when he was asked to explain quantum computing during a visit to the Perimeter Institute for Theoretical Physics in April 2016. It’s a great explanation — and great to see a non-scientist communicate science so very well:

Check out the full set of Sunday Science blog posts here.

What is Sunday Science?

Hello. I’m the freelance writer who gets tech. I have two degrees in Physics and, during my studies, I became increasingly frustrated with the complicated language used to describe some outstanding scientific principles. Language should aid our understanding — in science, it often feels like a barrier.

So, I want to simplify these science sayings and this blog series “Sunday Science” gives a quick, no-nonsense definition of the complex-sounding scientific terms you often hear, but may not completely understand.

If there’s a scientific term or topic you’d like me to tackle in my next post, fire an email to or leave a comment below.

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