A spectre is haunting our networked world. It’s the prospect of quantum computers. These are machines that harness some of the weirder properties of subatomic particles in ways that would make them exponentially more powerful than the computers we use today.
Existing computers are based on manipulating digital bits that can be either 1 (on) or 0 (off). Quantum machines, in contrast, work with qubits, which can be on and off simultaneously. (And, yes, I know that seems nuts, but then so does much of subatomic physics to the average layperson.) Such machines are fiendishly difficult to build, but about 80 or so small-scale ones already exist, with qubit counts ranging from five to 400. So that looming spectral presence is beginning to put on weight. And if researchers find a way of reliably scaling up these machines, then we will have moved into uncharted territory.
