We generalize the derivation of Leggett-Garg inequalities to systematically treat a larger class of experimental situations by allowing multiparticle correlations, invasive detection, and ambiguous detector results. Furthermore, we show how many such inequalities may be tested simultaneously with a single setup. As a proof of principle, we violate several such two-particle inequalities with data obtained from a polarization-entangled biphoton state and a semiweak polarization measurement based on Fresnel reflection. We also point out a nontrivial connection between specific two-party Leggett-Garg inequality violations and convex sums of strange weak values.
Dressel, J., Broadbent, C.J., Howell, J.C., Jordan, A.N., 2011. Experimental Violation of Two-Party Leggett-Garg Inequalities with Semiweak Measurements. Physical Review Letters 106, 040402. doi:10.1103/PhysRevLett.106.040402
American Physical Society