Enhancing phase-covariant channel performance with non-unitality

• URL: http://arxiv.org/abs/2212.04876v1
• Date: Fri, 9 Dec 2022 14:31:19 GMT
• Title: Enhancing phase-covariant channel performance with non-unitality
• Authors: Katarzyna Siudzi\'nska and Micha{\l} Studzi\'nski
• Abstract summary: We analyze quantum communication properties of phase-covariant channels depending on their degree of non-unitality. We show how to manipulate between unital and maximally non-unital maps by considering classical mixtures of quantum channels.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• 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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