After 30 months of fast-paced innovation in quantum algorithms, six research groups are hoping to hit paydirt. But there can be only one big winner—if there is a winner at all.

Right now, quantum computers are small and error-prone compared to where they’ll likely be in a few years. Even within those limitations, however, there have been regular claims that the hardware can ...

Peter Shor didn’t set out to break the internet. But an algorithm he developed in the mid-1990s threatened to do just that. In a landmark paper, Shor showed how a hypothetical computer that exploited ...