Quantum Computing: Where are we?

Christian Hall

The future of computing is most definitely a quantum one, in fact we're already there. But quantum computing so far has just scratched the surface of what could be possible. Harnessing the real compute power that lies behind the fundamental laws of physics is both fascinating for techies and a commercial battleground for the tech vendors. Let's take a look at the 'state' (you'll get the physics pun in a minute) of the quantum computing revolution and why the race is on to turn theory into reality.

Small beginnings

Quantum computing was first proposed in the early 1980s. In the most basic terms, quantum computing can perform calculations at a speed that simply can't be achieved by the building blocks of all computers in existence today. That's because all computers, no matter how numerous the cores or powerful the memory, operate on just two states - ones and zeros - binary, or simply 'bits'. Computing's most basic instructions are either on or off, but in the quantum world there can be almost any number of states at any one time. If you think of normal computing as a sphere with pieces of information at the two opposite poles, quantum computing is the same sphere but the information can exist at any point on that sphere. The bits become 'qubits'.

To put it another way, if you flip a coin you have two outcomes, heads or tails. If it were a quantum coin, you could land it in any position so that it was partly heads and partly tails - slightly weighted one way or the other (see the video above).

If that sounds rather simple, and not something that the greatest computing minds should have been puzzling over for decades, you're right. It's how you get to a qubit that's the hard part, and it comes down to some seriously weird physics at the atomic level... entanglement and superposition!

Quantum states

This is the part where we stop thinking about data and start thinking about laws of the impossibly small! Quantum entanglement describes the relationship between tiny particles across even vast distances whilst quantum superposition is the bizarre reality that things can be a mix of states other than two absolutes like 0 or 1. Then there's interference, where particles can be in and out of phase, giving them fundamentally different properties.

In fact, this science is so cutting edge that even a new form of light has been discovered for potential use in computing. It's mastering these curious properties of the physical world that opens the door to quantum computing and all the power it promises. How to take best advantage of these amazing properties of particles will keep the finest scientific minds busy for decades to come.

"it comes down to some seriously weird physics at the atomic level... entanglement and superposition!"

The Quantum Advantage

I mentioned earlier that quantum isn't just the future, it is actually here to some extent. IBM and D-Wave Systems both have quantum computers that can be used today in a cloud computing environment. Google and Intel are also in the game with their own versions.

Just a few weeks ago, IBM announced IBM Q System One, which allows public access to the capabilities of a 20-qubit quantum computer housed in a 9x9x9ft air-tight glass cube that maintains precisely the right temperature. Quantum computers are so sensitive to movement and temperature that only the strictest of controlled environments allow them to function without error.

However, the sensitivity of them isn't the thing to hold quantum computing back. The real problem is that there's nothing yet that a quantum computer can do, that the very best supercomputers can't. Though that's more to do with the way we think about computers and program them, rather than the possibilities of quantum computing not being what we thought. Our current state is called the 'quantum advantage', where we are on the cusp of quantum computers being able to do calculations faster than our very best supercomputers. But the holy grail of 'quantum supremacy', where the abilities of the quantum computer are simply impractical or impossible on a supercomputer, remains the next major milestone.

Quantum future

As we approach 2020, expect the next decade to be full of major breakthroughs in the world of quantum computing, many of which we can barely perceive today but could become routine by the 2030s. The complex scientific modelling achieved with quantum calculations could lead to incredible new discoveries and it's bound to follow classical computing in terms of miniaturisation and availability of the technology in future decades. It's no wonder the biggest tech firms are firmly invested in a quantum future.

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