Heisenberg-Weyl operator
= Heisenberg-Weyl operator
{c}
{title2=$W_{k,m}=X^kZ^m$}
On a $d$-dimensional <Hilbert space>, let $X|j\rangle=|j+1\bmod d\rangle$ and $Z|j\rangle=e^{2\pi ij/d}|j\rangle$. The $d^2$ unitaries $W_{k,m}=X^kZ^m$ form an orthogonal operator basis under the <Hilbert-Schmidt inner product>.