Figure 4

This plot illustrates the number of photons recorded per second in one SPCM (blue solid), two SPCMs (green dotted) and four SPCMs (red dash-dotted) with increasing pump power. The photons are collected by coupling (a) SMF and (b) MMF to the QRNG source. The raw data for one-bit generation is possible from photon counts obtained through two SPCMs and two-bit generation requires four SPCMs. Due to the path-entanglement and two-bit mapping, one can see nearly 1.7 times higher bits generation compared to the photons detected when SMF is used and when counts were well below the detector saturation point. When MMF is used at a high power in this setup, we eliminate the limitation imposed by the dead time of each detector which would have caused in a loss of number of photon detections. Distributing the detection events across multiple paths increases the effective saturation point by spreading the photon among all detectors. Thus, we could record around a total of 80 Mbps, while the single photon detectors have a saturation point close to 28 Mcps