9.7 Quantum circuits
We have now seen all the quantum gates we will need in this book, and it’s time to compose them into circuits.
The goal of a quantum algorithm as implemented in a circuit is to manipulate the qubits’ states so that the 0s and 1s we get when we measure have a very high probability of being the correct answer.
9.7.1 A basic circuit
I’ve done this already in simple cases, but let’s see what a basic circuit looks like from beginning to end.
The circuit in Figure 9.12 contains a quantum register with one qubit. The initialization phase is to the left of the first vertical dotted line. In this phase, we initialize qubit q0 to |0⟩. If we do not explicitly display |0⟩, you may assume that the qubit starts in that state. We call the horizontal line a wire...
