Number of quantum measurement outcomes as a resource

Abstract

Recently there have been fruitful results on resource theories of quantum measurements. Here we investigate the number of measurement outcomes as a kind of resource. We cast the robustness of the resource as a semi-definite positive program. Its dual problem confirms that if a measurement cannot be simulated by a set of smaller number of outcomes, there exists a state discrimination task where it can outperforms the whole latter set. An upper bound of this advantage that can be saturated under certain condition is derived. We also show that the possible tasks to reveal the advantage are not restricted to state discrimination and can be more general.