  Nowadays the most intriguing features of wave particle complementarity of
single photon is exemplified by the famous Wheeler's delayed choice experiment
in linear optics, nuclear magnetic resonance and integrated photonic device
systems. Studying the wave particle behavior in light and matter interaction at
single photon level is challenging and interesting, which gives how single
photons complement in light and matter interaction. Here, we demonstrate a
Wheeler's delayed choice experiment in an interface of light and atomic memory,
in which the cold atomic memory makes the heralded single photon divided into a
superposition of atomic collective excitation and leaked pulse, thus acting as
memory beam splitters. We observe the morphing behavior between particle and
wave of a heralded single photon by changing the relative proportion of quantum
random number generator, the second memory efficiency, and the relative storage
time of two memories. The reported results exhibit the complementarity behavior
of single photon under the interface of light atom interaction.
