  Born rule is key to understanding quantum mechanics based on the probability
amplitude for the measurement process of a physical quantity. Based on a
typical particle nature of a photon, the quantum feature of photon bunching on
a beam splitter between two output photons can be explained by Born rule even
without clear definition of the relative phase between two input photons.
Unlike conventional understanding on this matter, known as the Hong-Ou-Mandel
effect, here, we present a new interpretation based on the wave nature of a
photon, where the quantum feature of photon bunching is explained through phase
basis superposition of the beam splitter. A Mach-Zehnder interferometer is
additionally presented to support the correctness of the presented method. As a
result, our limited understanding of the quantum feature is deepened via phase
basis superposition regarding the destructive quantum interference. Thus, the
so-called mysterious quantum feature is now clarified by both the definite
phase relationship between paired photons and a new term of the phase basis
superposition of an optical system.
