  The puzzling properties of quantum mechanics, wave-particle duality,
entanglement and superposition, were dissected experimentally at past decades.
However, hidden-variable (HV) models, based on three classical assumptions of
wave-particle objectivity, determinism and independence, strive to explain or
even defeat them. The development of quantum technologies enabled us to test
experimentally the predictions of quantum mechanics and HV theories. Here, we
report an experimental demonstration of an entanglement-assisted quantum
delayed-choice scheme using a liquid nuclear magnetic resonance quantum
information processor. This scheme we realized is based on the recently
proposed scheme [Nat. Comms. 5:4997(2014)], which gave different results for
quantum mechanics and HV theories. In our experiments, the intensities and the
visibilities of the interference are in consistent the theoretical prediction
of quantum mechanics. The results imply that a contradiction is appearing when
all three assumptions of HV models are combined, though any two of the above
assumptions are compatible with it.
