Loss-based Experimental Test of Bohr's Complementarity Principle with   Single Neutral Atom
  An experimental test of quantum complementarity principle based on single neutral atom trapped in a blue detuned bottle trap was here performed. A Ramsey interferometer was used to assess the wavelike behavior or particle-like behavior with second $\pi/2$-rotation on or off. The wavelike behavior or particle-like behavior is characterized by the visibility $V$ of the interference or the predictability $P$ of which-path information, respectively. The measured results fulfill the complementarity relation $P^2+V^2\leq1$. Imbalance losses were deliberately introduced to the stem and find the complementarity relation is then formally "violated." All the experimental results can be completely explained theoretically by quantum mechanics without considering the interference between wave and particle behaviors. This observation complements existing information concerning the BCP based on wave-particle duality of massive quantum. 
Zhihui Wang, Yali Tian, Chen Yang, Pengfei Zhang, Gang Li and Tiancai   Zhang
quant-ph