The basic idea—tap into quantum physics to make immensely powerful computers—isn't new. Nobel-winning physicist Richard Feynman is generally credited with first suggesting that in 1982. But in the past few years the concept has started to become more real.

Google, IBM, Intel, Microsoft, and a pack of startups are all building and testing quantum computing hardware and software. They're betting that these machines will lead to breakthroughs in areas such as chemistry, materials science, logistical planning such as in factories, and perhaps artificial intelligence.

It will probably be years before the technology is mature enough to be broadly practical. But the potential gains are so large that companies such as JP Morgan and Daimler are already experimenting with early machines from IBM.