Quantum computing has been vaunted as the future of technology. Way back in 1981, famous physicist Richard Feynman urged the world to build a quantum computer. He said "Nature isn't classical, dammit, and if you want to make a simulation of nature, you'd better make it quantum.”
It might take a world renounced physicist to understand all of the implications of quantum computing but anyone can grasp the basics. Over a century ago people realised that nature’s stuff behaves very differently on the very small (“quantum”) scale. Something called the Uncertainty Principle means that you cannot tell exactly where something is and what it’s doing at exactly the same time. Furthermore, very small things very close to each other can get tangled up and interfere with each other. This quantum view of the world has been very successful, enabling us to build everything from LED’s to nuclear reactors.
Taken into the world of computing, today’s machines look much like the classical world did in the 19th century. The computer always comes out with a definite answer, literally a series of 1’s and 0’s and each part of the computer (“bit”) is either a 1 or 0 – and nothing inbetween.
Quantum computers essentially have very small bits (called qubits”) which, due to uncertainty, can’t be said to be either 1 or 0 but exist in some sort of fuzzy state inbetween. If you looked at a single qubit in detail, sometimes it might be a 1 and other times a 0. Put a lot of them together and it means that there’s bound to be the “right” answer in there somewhere, the problem is finding it – which you do by sampling again and again. It may seem that quantum computers may not offer that much advantage, but the tanglement property also means parts of the quantum computer see and influence other parts – and so in simple terms the right answer re-enforces itself and is more likely to appear.
If all this seems a bit esoteric, then it’s worth realising that today’s world is built on things like public key cryptographic systems based on prime number problems that take today’s computer too long to solve. However, quantum computers can solve such puzzles much (much) quicker. We may have to rethink how we do security.
Going back to Google’s announcement. Quantum supremacy is not some Terminator like domination of the machine but simply means that a quantum computer may be able to do one narrow, closely defined task better than a classical one. But many see quantum computers as a key part of the future and something to invest in now. Quantum computing regularly makes the top 10 lists of things that really are going to change our world.
Google, and Microsoft and others are investing billions in quantum computing. The qubits may be fuzzy but their business thinking is not.
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