Channel ensembles reveal how noise affects quantum data transfer

Matthew Duschenes of Los Alamos National Laboratory, University of Waterloo, and Perimeter Institute for Theoretical Physics, alongside colleagues, has established a new framework to compute moment operators for ensembles of quantum channels for all moment orders. The work gives hierarchies between these ensembles operational meaning with the definition of channel t-designs. Different types of noise impact these operators in opposing ways; depolarizing noise decreases the norm, while amplitude damping noise increases it. This research generalizes noise-induced concentration phenomena to channel-design-induced phenomena and includes the discovery of a block-orthogonal basis for permutations that simplifies moment calculations. Hierarchies between ensembles of quantum channels are now theoretically defined, allowing for comparison and ranking based…