The dataset contains experimental measurements (photon counts) of a polarization-based quantum channel equipped with different configurations. This dataset has been generated within the framework of the project "Experimental Assesment of Fast Quantum Key Distribution", a project funded by the NGIatlantic.eu 3rd Open Call, which aims at deploying the EU-US Experimental Quantum Communication Laboratory (EQC Lab) with participation of Universitat Politecnica de Catalunya (UPC, as EU partner) and University of California Davis (UCDavis, as US partner).