In the fall of 2019, Google told the world it had reached “quantum supremacy.”It was a significant scientific milestone that some compared to the first flight at Kitty Hawk. Harnessing the mysterious powers of quantum mechanics, Google had built a computer that needed only three minutes and 20 seconds to perform a calculation that normal computers couldn’t complete in 10,000 years.But more than two years after Google’s announcement, the world is still waiting for a quantum computer that actually does something useful. And it will most likely wait much longer. The world is also waiting for self-driving cars, flying cars, advanced artificial intelligence and brain implants that will let you control your computing devices using nothing but your thoughts.Silicon Valley’s hype machine has long been accused of churning ahead of reality. But in recent years …
