A class of Schwarz qubit maps with diagonal unitary and orthogonal symmetries

• URL: http://arxiv.org/abs/2404.10895v1
• Date: Tue, 16 Apr 2024 20:37:16 GMT
• Title: A class of Schwarz qubit maps with diagonal unitary and orthogonal symmetries
• Authors: Dariusz Chruściński, Bihalan Bhattacharya,
• Abstract summary: A class of unital qubit maps displaying diagonal unitary and symmetries is analyzed. We provide a complete characterization of this class of maps showing intricate relation between positivity, operator Schwarz inequality, and complete positivity. Our analysis leads to generalization of seminal Fujiwara-Algoet conditions for Pauli quantum channels.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: A class of unital qubit maps displaying diagonal unitary and orthogonal symmetries is analyzed. Such maps already found a lot applications in quantum information theory. We provide a complete characterization of this class of maps showing intricate relation between positivity, operator Schwarz inequality, and complete positivity. Finally, it is shown how to generalize the entire picture beyond unital case (so called generalized Schwarz maps). Interestingly, the first example of Schwarz but not completely positive map found by Choi belongs to our class. As a case study we provide a full characterization of Pauli maps. Our analysis leads to generalization of seminal Fujiwara-Algoet conditions for Pauli quantum channels.

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