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.

Technology veteran IBM on Tuesday laid out a plan to have a "practical" quantum computer tackling big problems before the end of this decade. Current quantum ...

The company says it has cracked the code for error correction and is building a modular machine in New York state. IBM announced detailed plans today to build an ...