In this section we introduce quantum circuits, a common notation used for communicating quantum algorithms.
We normally start with our qubits in the state |0⟩, and perform a sequence of operations on them. We use quantum circuits to show this: each line represents a qubit, each box represents an operation and the operations are carried out in chronological order from left to right.
We now know enough to create our first quantum algorithm! We start with possibly the most simple algorithm we can think of on a quantum computer- a true random number generator.
After the H-gate, the state of each qubit is |+⟩ which gives equal probability of measuring |0⟩ and |1⟩. This is a truly quantum algorithm (cannot be perfomed on a classical computer).