Regularized maximal fidelity of the generalized Pauli channels

Abstract

We consider the asymptotic regularization of the maximal fidelity for the generalized Pauli channels, which is a problem similar to the classical channel capacity. In particular, we find the exact formulas for the extremal channel fidelities and the maximal output $\ensuremath{\infty}$-norm. For wide classes of channels, we show that these quantities are weakly multiplicative. Finally, we find the regularized maximal fidelity for the channels satisfying the time-local master equations.