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

TL;DR

This paper investigates how erasing beam path information, either during measurement or after, affects Hong-Ou-Mandel interference, showing that physical erasure during measurement is necessary for interference.

Contribution

It demonstrates that Hong-Ou-Mandel interference depends critically on the method of erasing beam path information, emphasizing the importance of physical measurement processes.

Findings

Interference occurs only when beam path information is erased during measurement.

Erasing temporal information after measurement does not produce interference.

Physical measurement process is crucial for observing Hong-Ou-Mandel interference.

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.