Economical realization of phase covariant devices in arbitrary   dimensions
  We describe a unified framework of phase covariant multi user quantum transformations for d-dimensional quantum systems. We derive the optimal phase covariant cloning and transposition tranformations for multi phase states. We show that for some particular relations between the input and output number of copies they correspond to economical tranformations, which can be achieved without the need of auxiliary systems. We prove a relation between the optimal phase covariant cloning and transposition maps, and optimal estimation of multiple phases for equatorial states. 
Francesco Buscemi, Giacomo Mauro D'Ariano, and Chiara Macchiavello