Year: 2026
Type: article
Abstract: We present a complete characterization of diagonal unitary covariant (DU-covariant) superchannels, i.e., higher-order transformations transforming quantum channels into themselves. Necessary and sufficient conditions for complete positivity and trace preservation are derived and the canonical decomposition describing DU-covariant superchannels is provided. The presented framework unifies and extends known families of covariant quantum channels and enables explicit analysis of their action on physically relevant examples, including amplitude-damping, bit-flip, and Pauli channels. Our results provide a practical toolbox for symmetry-restricted higher-order quantum processes and offer a setting for exploring open problems such as the celebrated positive partial transpose-squared conjecture.
Source: Journal of Mathematical Physics
DOI: 10.1063/5.0326157
Authors: Dariusz Chruściński, Vivek Pandey, Sohail
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7117967505