Quantum computing has long lived in the realm of lab demos and bold PowerPoint slides, but two of the industry’s biggest players now say the first truly useful machines are less than five years away.

For the past year, I kept bringing the same story to my editor: quantum computers are on the edge of becoming useful for scientific discovery. Of course, that has always been the goal. The idea of ...

A vital ingredient for making quantum computers truly useful just might be conventional computers. That was the message from a gathering of researchers this month, which explained that classical ...