NumberOperator¶

Module: pennylane

class NumberOperator(wires)[source]

The photon number observable $$\langle \hat{n}\rangle$$.

The number operator is defined as $$\hat{n} = \a^\dagger \a = \frac{1}{2\hbar}(\x^2 +\p^2) -\I/2$$.

When used with the expval() function, the mean photon number $$\braket{\hat{n}}$$ is returned.

Details:

• Number of wires: 1

• Number of parameters: 0

• Observable order: 2nd order in the quadrature operators

• Heisenberg representation:

$\begin{split}M = \frac{1}{2\hbar}\begin{bmatrix} -\hbar & 0 & 0\\ 0 & 1 & 0\\ 0 & 0 & 1 \end{bmatrix}\end{split}$
Parameters: wires (Sequence[int] or int) – the wire the operation acts on