= Weight of a Pauli operator
{title2=$\operatorname{wt}(P)=|\{j:P_j\ne I\}|$}
= Pauli weight
{c}
{synonym}
The weight of a tensor-product <Pauli operator> is the number of nonidentity local factors; its global phase is ignored. Products satisfy $\operatorname{wt}(P^\dagger Q)\leq\operatorname{wt}(P)+\operatorname{wt}(Q)$ because their support is contained in the union of the two supports. The <quantum code distance> uses this weight to measure the smallest undetectable nontrivial action on logical information.
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