Manuscript Em03-E@1 · Em03-E-v1.tex · section · c4b07e6a

Exactly private individual cells

E2: complete radiation-channel calculation › Exactly private individual cells · lines 707–717

Em03-E@1#eq:twirl

Pauli averaging obeys

\frac{1}{4} a, b \sum P_{ab} X P_{ab}^{†} = tr (X) \frac{I _{2}}{2} .

This follows by expanding $X$ in the Pauli basis: every nonidentity coefficient cancels.

Displayed formulas in this passage

Em03-E@1#eq:twirl · line 710
$\frac{1}{4} a, b \sum P_{ab} X P_{ab}^{†} = tr (X) \frac{I _{2}}{2} .$