An extremely low-noise heralded single-photon source without temporal post-selection

With the recent progresses in quantum technologies, single photon sources have gained a primary relevance. Here we present a heralded single photon source characterized by an extremely low level of noise photons, realized by exploiting low-jitter electronics and detectors and fast custom-made electronics used to control an optical shutter (a LiNbO3 waveguide optical switch) at the output of the source. This single photon source showed a second-order autocorrelation function g((2)) (0) = 0 : 005(7), and an Output Noise Factor (defined as the ratio of noise photons to total photons at the source output) of 0 : 25(1)%, among the best ever achieved.