Quantum computers, we are assured, are a game-changing device that is about twenty years away. Such assurances have been made for about twenty years now.

A reasonable person might therefore worry that quantum computing is going the way of cold fusion.

The central goal of my work in quantum computing is to find out whether the quantum future looks like cold fusion. I usually divide this challenge into two big questions:

How do we build a quantum computer, and what do we do with it when it is built?

Though I will focus on my own investigations into these two questions, I aim to make this talk accessible to a general physics audience.  I will therefore spend most of the talk discussing basic quantum computing, characterisation and control of quantum systems, fault-tolerance threshold theorems, algorithmic speedups and quantum supremacy.