# Measure operation

Namespace: Microsoft.Quantum.Intrinsic

Package: Microsoft.Quantum.Type1.Core

Performs a joint measurement of one or more qubits in the specified Pauli bases.

```
operation Measure (bases : Pauli[], qubits : Qubit[]) : Result
```

## Description

The output result is given by the distribution:
\begin{align}
\Pr(\texttt{Zero} | \ket{\psi}) =
\frac12 \braket{
\psi \mid|
\left(
\boldone + P_0 \otimes P_1 \otimes \cdots \otimes P_{N-1}
\right) \mid|
\psi
},
\end{align}
where $P_i$ is the $i$th element of `bases`

, and where
$N = \texttt{Length}(\texttt{bases})$.
That is, measurement returns a `Result`

$d$ such that the eigenvalue of the
observed measurement effect is $(-1)^d$.

## Input

### bases : Pauli[]

Array of single-qubit Pauli values indicating the tensor product factors on each qubit.

### qubits : Qubit[]

Register of qubits to be measured.

## Output : Result

`Zero`

if the $+1$ eigenvalue is observed, and `One`

if
the $-1$ eigenvalue is observed.

## Remarks

If the basis array and qubit array are different lengths, then the operation will fail.

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