(color online) Experimental result of quantum interference between heralded single photon and coherent state in optical fiber. The pattern of Hong–Ou–Mandel interference is represented by the relationship between three-fold coincidence counts versus the position of the translation stage, X, in the scheme, when the intensity of the coherent state is fixed at 0.04 photon/pulse. After subtracting three-fold background coincidences of 57 counts/50 min from the original data, the visibility 82±11% is obtained. Because of the small three-fold coincidence count, the relative statistical error of each data point is large, which causes the data points in the border to deviate a little from the theoretical curve.