Local extrema of entropy functions under tensor products

Shmuel Friedland, Gilad Gour, Aidan Roy

Published 2011-05-26Version 1

We show that under a certain condition of local commutativity the minimum von-Neumann entropy output of a quantum channel is locally additive. We also show that local minima of the 2-norm entropy functions are closed under tensor products if one of the subspaces has dimension 2.