  Wave-particle duality constitutes one of the most intriguing features in
quantum physics. A well-known gedanken experiment that provides evidence for
this is the Wheeler's delayed-choice experiment based on a Mach-Zehnder
interferometer. Many different versions of delayed-choice experiments have been
conducted with both classical and quantum detecting devices. Recently, it was
proposed that the delayed-choice experiment could be devised from the
perspective of device-independent prepare-and-measure scenario. In our work, we
experimentally realize this modified version with a deterministic single-photon
source, and examine the wave-particle objective in a causal-modeled scheme
without assistance of entanglement, which is achieved by violating the
dimension witness inequalities. Our experiment also provides an intriguing
perspective and exhibits the benefits of studying quantum theory from the
casual model point of view.
