Ultra-fast Hong-Ou-Mandel interferometry via temporal filtering

Heralded single photons (HSPs) generated by spontaneous parametric down-conversion (SPDC) are useful resource to achieve various photonic quantum information processing. Given a large-scale experiment which needs multiple HSPs, increasing the generation rate with suppressing higher-order pair creation is desirable. One of the promising ways is to use a pump laser with a GHz-order repetition rate. In such a high repetition rate regime, however, single-photon detectors can only partially identify the pulses. Hence, we develop a simple model to consider that effect on the spectral purity, and experimentally demonstrate a high-visibility Hong-Ou-Mandel interference between two independent HSPs generated by SPDC with 3.2 GHz-repetition-rate mode-locked pump pulses. The observed visibility of 0.88(3) is in good agreement with our theoretical model. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

By utilizing a pump laser with a high repetition rate, the study increased the generation rate of single photons and successfully suppressed the creation of higher-order pairs. The research team developed a simple model to consider the effect on spectral purity, and experimentally demonstrated high-visibility interference between two independent HSPs generated by SPDC.