Hong-Ou-Mandel interference depends on the method of the erasing the beam path information

Abstract

We study how the information of the beam path is related to the Hong-Ou-Mandel interference with two pulsed light sources. Through a simple model in which two photons in the form of pulses pass a beamsplitter and are observed at two detectors, we investigate how, during the measurement process, information about the paths of the two photons can be erased. There are two ways to clear the information of the beam path, the first being that from the beginning, during the physical measurement process, the time information is not obtained. The other is after measuring the information, to erase the temporal information in the data analyzing process. We show that Hong-Ou-Mandel interference can be obtained only when the beam path inofrmation is cleared from the physical measurement process.