If you want to get into quantum computing, there’s no way around it: you will have to master the cloudy concept of the quantum gate. Like everything in quantum computing, not to mention quantum mechanics, quantum gates are shrouded in an unfamiliar fog of jargon and matrix mathematics that reflects the quantum mystery. My goal in this post is to peel off a few layers of that mystery. But I’ll save you the suspense: no one can get rid of it completely. At least, not in 2018. All we can do today is reveal the striking similarities and alarming differences between classical gates and quantum gates, and explore the implications for the near and far future of computing.