In chapter 9, we used a number of new Q# features like user-defined types (UDTs) and running programs from Python hosts to help us write a quantum program that could estimate phases. As we will see in this chapter, phase estimation is commonly used in quantum algorithms to build up larger and more complex programs. In this chapter, we’ll look at our first practical application area: chemistry.
So far in this book, we’ve learned how to use quantum devices to do everything from chat with our friend Eve to help decide the fate of kings. In this chapter, though, we’ll get the chance to do something a bit more practical.
Note
Now that we have what we need to solve harder problems with quantum computers, this chapter’s scenario is a little more complicated than most of our earlier games and scenarios. Don’t worry if things don’t make sense off the bat. Take your time and read things more slowly; we promise it will be worth your while!