Regularized maximum pure-state input-output fidelity of a quantum channel

摘要

As a toy model for the capacity problem in quantum information theory we investigate finite and asymptotic regularizations of the maximum pure-state input-output fidelity F(N) of a general quantum channel N. We show that the asymptotic regularization F (N) is lower bounded by the maximum output∞-norm ν_∞(N) of the channel. For N being a Pauli channel, we find that both quantities are equal.