How to maximize the capacity of general quantum noisy channelsThis paper is dedicated to the 70th anniversary of Prof. Paolo Tombesi: friend, colleague, scientist.

A general quantum noisy channel is analyzed, wherein the transmitted qubits may experience symmetrybreaking decoherence, along with memory effects. We examine generalized Bellbasis and find that the optimal basis is not the fully entangled one, but a combination of factorized and partiallyentangled states in the presence of memory, asymmetry and the statebias of the noise. Capacitymaximization is shown to be achievable by combining temporal shaping of the transmitted qubits and optimal basis selection. [ABSTRACT FROM AUTHOR]