Experimental Test of Born's Rule by Inspecting Third-Order Quantum   Interference on a Single Spin in Solids
  As a fundamental postulate of quantum mechanics, Born's rule assigns probabilities to the measurement outcomes of quantum systems and excludes multi-order quantum interference. Here we report an experiment on a single spin in diamond to test Born's rule by inspecting the third-order quantum interference. The ratio of the third-order quantum interference to the second-order in our experiment is ceiled at the scale of $10^{-3}$, which provides a stringent constraint on the potential breakdown of Born's rule. 
Fangzhou Jin, Ying Liu, Jianpei Geng, Pu Huang, Wenchao Ma, Mingjun   Shi, Chang-Kui Duan, Fazhan Shi, Xing Rong and Jiangfe...
quant-ph