Top tech: Quantum computing

If your laptop’s been on the go-slow and the spinning pizza’s been on overtime as you try to crunch a few numbers, fear not – quantum computing promises to deliver processing speeds you’ve never dreamed of. It won’t be on your desktop exactly, but it’s good to know we’ll soon have a new superhero to tackle our daunting problems… 

What is it? 

If you don’t have a degree in quantum mechanics, the first thing to understand about quantum computing is that understanding it is no easy matter.

A quantum computer is fundamentally different from conventional computers in that it is non-binary, and it doesn’t operate in the same linear, sequential fashion. The computers we use today are binary in the sense that they store data and perform calculations using the digits 0 and 1; each ‘bit’ of storage has one value or the other, and there is no in-between. 

In quantum computing, data is stored in ‘qubits’ that can hold the values 0 and 1 simultaneously, as well as any proportion of the two.

How? Don’t ask. This is known as the superposition – think about it in relation to a switch that can be in two positions – ‘on’ or ‘off’ – but what it means is that while four conventional computer bits can hold one of 16 different binary combinations, four qubits can hold all 16 simultaneously.

Add qubits and the quantity of data that can be held and processed soars – 20 qubits can store a staggering one million combinations in parallel.

Why is this important?

Suppose you were trying to find a passcode, a conventional computer would have to try out each combination in turn; the quantum computer can try them all out simultaneously, taking a tiny fraction of the time to achieve the same result. This exponential acceleration in processing power is known as the quantum speedup. 

Another important concept to get your head around is entanglement; this is a characteristic/property that means each qubit can react to each of the others simultaneously no matter how far they are apart. So if you can determine the state or value of one qubit, you can deduce the state of all its partners without having to look. 

The key thing is that a quantum computer can take in a vast amount of data, process it all in one go, perform the most complex calculations, and come up with a single answer. If you want to know more than that, you’ll have to read a book.

What does it look like? 

Search for images of a quantum computer and you’ll likely come up with something that looks like a weird chandelier, all wires and tubes and components hanging off a series of discs. The models that have been demonstrated until now rely upon having electrical circuits that are supercooled at a temperature closer to that in outer space.

IBM, Google and Microsoft are among the better known companies that have put models into public circulation. Honeywell has recently revealed that it has developed its own quantum computer, which uses a different technology – trapped ions held in place by electromagnetic forces – to create the superposition.

What’s it for? 

Key applications that have been identified include carrying out far more accurate and long-term weather forecasts; simulating molecules in the process of drug research; materials processing; high-security encryption; and moving data from one place to another without transmitting it. 

When can I get one?
 
You’ll probably never be able to buy a quantum computer for personal use, but there are a number already on the market with limited capabilities. Minimum price today is around $15m and the sky’s the limit – according to one estimate, each qubit costs $10,000.

In October last year, Google announced that it had achieved ‘quantum supremacy’ – the ability to solve a problem that conventional computers cannot. IBM promptly rubbished that. No doubt we’ll be hearing a lot more from both of them.