Experimental Test of Complementarity by Nuclear Magnetic Resonance   Techniques
  We have tested complementarity for the ensemble-averaged spin states of nuclei $^{13}$C in the molecule of $^{13}$CHCl$_{3}$ by the use of the spin states of another nuclei $^{1}$H as the path marker. It turns out that the wave-particle duality holds when one merely measures the probability density of quantum states, and that the wave- and particle-like behavior is simultaneously observed with the help of measuring populations and coherence in a single nuclear magnetic resonance(NMR) experiment. Effects of path-marking schemes and causes of the appearance and disappearance of the wave behavior are analysed. 
Xiwen Zhu, Ximing Fang, Xinhua Peng, Mang Feng, Kelin Gao, and Fei Du   (Wuhan Institute of Physics and Mathematics, Chinese...