Information capacity of quantum communication under natural physical assumptions

The quantum prepare-and-measure scenario has been studied under various physical assumptions on the emitted states. Here, we first discuss how different assumptions are conceptually and formally related. We then identify one that can serve as a relaxation of all others, corresponding to a limitation on the one-shot accessible information of the state ensemble. This motivates us to study the optimal state discrimination probability of a source subject to these various physical assumptions. We derive general and tight bounds for states restricted by their quantum dimension, their vacuum component, an arbitrary uniform overlap, the magnitude of higher-dimensional signals and the experimenter's trust in their device. Our results constitute a first step towards a more unified picture of semi-device-independent quantum information processing.