Violating the LG inequality with K−.
(a) The corresponding values for individual correlations K(t1,t2), K(t2,t3) and K(t1,t3) to get K− in the inset of (b). The solid line, dashed line and dotted line are the corresponding theoretical predictions (the solid line and the dashed line completely overlap and only the solid line can be seen). The x axis represents the total thickness of quartz plates between t1 and t2. (b) The envelope evolution of K−. Red dots represent the experimental results. Solid lines are the theoretical fittings employing equation (3). The dashed line represents the classical limit, −1. The x axis represents the total thickness of quartz plates between t1 and t2. The inset displays the oscillation between the maximum and minimum in the blue dashed pane (the x axis represents the total thickness of quartz plates between t1 and t2 and the y axis represents K−). Error bars correspond to the random fluctuations of each measured coincidence count and the tilt uncertainties of quartz plates. λ 0 = 0.78 μm.