# Is the process on initialization of qubits unitary?

It is said in some texts, that quantum computer undergoes only 2 types of transofrmations:

1) unitary evolution while computing

and

2) non-unitary transformation while reading result (output).

Initialization is non-unitary (at least if you don't know the state your qubits are in before that). Let's say you want to initialize your qubits in the state $\lvert0\rangle$. First, you need to measure each qubit in some basis (say, $\{\lvert0\rangle,\lvert1\rangle\}$) -- this is the non-unitary part -- and now, if the result was $\lvert1\rangle$, you need to rotate $\lvert1\rangle$ to $\lvert0\rangle$ (which is unitary).