"Also, what is the relationship, if any, between quantum computing and AI? Are these technologies complementary?"

AI is limited in part by the computation available at training and runtime. If your computer is 10^X times faster, then your model is also "better". Thats why we have giant warehouses full of H100 chips pulling down a few megawatts from the grid right now. Quantum computing could theoretically allow your phone to do that.