**Inputs:**

1. A real number $\alpha$.
2. A non-negative real number $\beta = \sqrt{1 - \alpha^2}$.
3. A real number $\theta$.
4. A qubit in state $\ket{0}$.

**Goal:** Transform the qubit into state $\alpha\ket{0} + e^{i\theta}\beta\ket{1}$.

> Since only the relative amplitudes and relative phase have any physical meaning, this allows you to prepare any single-qubit quantum state you want to.
