Enhancing phase-covariant channel performance with non-unitality

Abstract

We analyze quantum communication properties of phase-covariant channels depending on their degree of non-unitality. In particular, we derive analytical formulas for minimal and maximal channel fidelity on pure states and maximal output purity. Next, we introduce a measure of non-unitality and show how to manipulate between unital and maximally non-unital maps by considering classical mixtures of quantum channels. Finally, we prove that maximal fidelity and maximal output purity increase with non-unitality and present several examples. Interestingly, non-unitality can also prolong quantum entanglement and lead to its rebirth.

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Cited by in corpus (4)

• (Thermo-)dynamics of the spin-boson model in the weak coupling regime: Application as a quantum battery
• Effective dynamics of qubit networks via phase-covariant quantum ensembles
• Improving classical capacity of qubit dynamical maps through stationary state manipulation
• Covariant decomposable maps on C*-algebras and quantum dynamics