The wave-particle duality of a single atom has indeed been demonstrated through a real-life experiment known as the double-slit experiment. This experiment was conducted by several research groups, and one notable study was published in 1999 by Markus Arndt, Olaf Nairz, Julian Voss-Andreae, Claudia Keller, Gerbrand van der Zouw, and Anton Zeilinger.
In this experiment, the researchers used a double-slit apparatus similar to the one used in the famous double-slit experiment with light. However, instead of using photons, they used a beam of atoms (specifically, fullerene molecules or Cāā). The fullerene molecules were sent through a beam splitter, creating two paths, and then passed through a pair of slits. The atoms were detected on a screen placed beyond the slits.
What the researchers observed was an interference pattern on the screen, which indicated that individual atoms exhibited wave-like behavior. This interference pattern emerged when atoms were sent through the slits one by one, demonstrating that even a single atom can exhibit wave-like properties and interfere with itself.
The 1999 experiment by Arndt et al. provided strong evidence for the wave-particle duality of atoms, confirming that particles at the atomic scale can exhibit both particle-like and wave-like characteristics, similar to what had been observed with photons in earlier double-slit experiments.
It's worth noting that the wave-particle duality is a fundamental principle of quantum mechanics and has been supported by numerous experiments, including those involving particles such as electrons, neutrons, and even larger molecules like fullerene.