Entropic uncertainty relations for extremal unravelings of super-operators

Abstract

A way to pose the entropic uncertainty principle for trace-preserving super-operators is presented. It is based on the notion of extremal unraveling of a super-operator. For a given input state, different effects of each unraveling result in some probability distribution at the output. As is shown, all Tsallis’ entropies of positive order as well as some of Rényi's entropies of this distribution are minimized by the same unraveling of a super-operator. Entropic relations between a state ensemble and the generated density matrix are revisited in terms of both the adopted measures. Using Riesz's theorem, we obtain two uncertainty relations for any pair of generalized resolutions of the identity in terms of the Rényi and Tsallis entropies. The inequality with Rényi's entropies is an improvement of the previous one, whereas the inequality with Tsallis’ entropies is a new relation of a general form. The latter formulation is explicitly shown for a pair of complementary observables in a d-level system and for the angle and angular momentum. The derived general relations are immediately applied to extremal unravelings of two super-operators.