Developing a photon-number-resolving detection chain for quantum communication protocols involving mesoscopic states of light

We present the characterization of a photon-number-resolving detection chain based on Silicon photomultipliers (SiPM) coupled to a 14 bit, 1 Gs\s digital acquisition system embedding an FPGA-based signal processing pipeline that performs real-time baseline subtraction, digital deconvolution, and charge integration. Three SiPM models manufactured by Hamamatsu are tested and compared in the mesoscopic intensity regime using both classical coherent states and quantum twin-beam states, enabling a systematic investigation of the effects of pixel pitch, pile-up, and photon detection efficiency on the detector performance.