SEATTLE — The tech giants are locked in a race. It might not end for another decade, and there might not be just one winner. But, at the finish line, the prize they promise is a speedy machine, a quantum computer, that will crack in minutes problems that can’t be solved at all today. Builders describe revolutionary increases in computing power that will accelerate the development of artificial intelligence, help design new drugs and offer new solutions to help fight climate change. Ready. Set. Quantum. Relying on principles of physics and computer science, researchers are working to build a qu…