The big promise of the next era of supercomputing is speed: To perform the feats of number-crunching needed to run artificial intelligence programs, the coming generation of data processors will tap the properties of quantum physics to deliver a leap in problem-solving power. In the case of the “gigafactory of compute” that billionaire Elon Musk seeks to build on an industrial site in Memphis, this buzzy new brand of thinking machine also comes with an incredibly accelerated development timeline...