Experimental investigation of quantum Simpson's paradox
Yulong Li, Jian‐Shun Tang, Yi‐Tao Wang, Yu-Chun Wu, Yong-Jian Han, Chuan‐Feng Li, Guang‐Can Guo, Ying Yu, Mi-Feng Li, Guowei Zha, Haiqiao Ni, Zhichuan Niu · Physical Review A · 2013
The well-known Simpson's paradox, or Yule-Simpson (YS) effect, is often encountered in social-science and medical-science statistics. It occurs when the correlations present in different groups are reversed if the groups are combined. Simpson's paradox also exists in quantum measurements. In this Brief Report, we experimentally realized two analogous effects: the quantum-classical YS effect and the quantum-quantum YS effect in the quantum-dot system. We also compared the probability of obtaining those two effects under identical quantum measurements and found that the quantum-quantum YS effect is more likely to occur than the quantum-classical YS effect.