Unital Positive Maps and Quantum States
M. Asorey, Andrzej Kossakowski, Giuseppe Marmo, E. C. G. Sudarshan · Open Systems & Information Dynamics · 2008
We analyze the structure of the subset of states generated by unital completely positive quantum maps. A witness certifying that a state does not belong to the subset generated by a given map is constructed. We analyse the representations of positive maps and their relation to quantum Perron-Frobenius theory.