Pauli-mixture parametrization of qubit depolarization
= Pauli-mixture parametrization of qubit depolarization
{c}
{title2=$\eta=(4p-1)/3$}
If the identity is applied with probability $p$ and the three nonidentity <Pauli operators> each with probability $(1-p)/3$, the <Bloch vector> retention factor is $(4p-1)/3$. Thus complete depolarization occurs at $p=1/4$, not at zero. The <Holevo capacity of a qubit depolarizing channel> becomes $1-h_2((2p+1)/3)$ in this identity-probability parametrization.