# Built-in quantum instructions¶

This section describes built-in non-unitary operations.

## Initialization¶

The statement `reset qubit|qubit[];`

resets a qubit or quantum register to the state
\(|0\rangle\). This corresponds to a partial trace over those qubits
(i.e. discarding them) before replacing them with
\(|0\rangle\langle 0|\). Reset is shown in Fig. 2.

```
// Initialize and reset a register of 10 qubits
qubit[10] qubits;
reset qubits;
```

## Measurement¶

The statement `bit|bit[] = measure qubit|qreg;`

measures the qubit(s) in the \(Z\)-basis and assigns
the measurement outcome(s) to the target bit(s). For backwards
compatibility this is equivalent to `measure qubit|qubit[] -> bit|bit[];`

which is also supported. Measurement
corresponds to a projection onto one of the eigenstates of \(Z\),
and qubit(s) are immediately available for further quantum computation.
Both arguments must be register-type, or both must be bit-type. If both
arguments are register-type and have the same size, the statement `b = measure a;`

broadcasts to `b[j] = measure a[j];`

for each index `j`

into register `a`

. Measurement is shown in
Fig. 3.

```
// Initialize, flip and measure a register of 10 qubits
qubit[10] qubits;
bit[10] bits;
x qubits;
bits = measure qubits;
```