Though this article does not describe a full-blown nand2tetris project, it is inspired by the course. In it, you learn how to build all possible logic gates exclusively out of NAND gates. And while you are encouraged to use your growing library of logic gates to in turn build more and more complex logic gates, even the most complex logic gates are fundamentally nothing more than large collections of NAND gates.
The point of this article is that you can build quantum logic gates in a similar manner. There may definitely be better ways — the AND gate is a perfect example — but you can still build your algorithms even if you don’t know those better ways. For example, if you don’t know the best way to implement a quantum OR gate — there definitely is one — you can still build the OR gate functionality that you need.
This article assumes that that you, the reader, are familiar with logic gates.
NAND
The Hadamard gates allow for all possible input combinations: 00, 01, 10, and 11. The NAND gate is simply an AND gate (Toffoli gate) with it’s output negated (reversed).
