  Resource theories are broad frameworks that capture how useful objects are in
performing specific tasks. In this paper we devise a formal resource theory
quantum measurements, focusing on the ability of a measurement to acquire
information. The objects of the theory are equivalence classes of positive
operator-valued measures (POVMs), and the free transformations are changes to a
measurement device that can only deteriorate its ability to report information
about a physical system. We show that catalysis and purification, protocols
that are possible in other resource theories, are impossible in our resource
theory for quantum measurements. Standard measures of information gain are
shown to be resource monotones, and the resource theory is applied to the task
of quantum state discrimination.

Quantum Physics