Explainer: What Is a Quantum Computer?

How it works, why it’s so powerful, and where it’s likely to be most useful first

MIT Technology Review
MIT Technology Review

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Photo: Justin Fantl, courtesy of Rigetti Computing

By Martin Giles

A quantum computer harnesses some of the almost-mystical phenomena of quantum mechanics to deliver huge leaps forward in processing power. Quantum machines promise to outstrip even the most capable of today’s — and tomorrow’s — supercomputers.

They won’t wipe out conventional computers, though. Using a classical machine will still be the easiest and most economical solution for tackling most problems. But quantum computers promise to power exciting advances in various fields, from materials science to pharmaceuticals research. Companies are already experimenting with them to develop things like lighter and more powerful batteries for electric cars, and to help create novel drugs.

The secret to a quantum computer’s power lies in its ability to generate and manipulate quantum bits, or qubits.

What is a qubit?

Today’s computers use bits — a stream of electrical or optical pulses representing 1s or 0s. Everything from your…

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MIT Technology Review
MIT Technology Review

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