= Aspect switching experiment
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In 1982, <Alain Aspect>, <Jean Dalibard> and <Gérard Roger> used a <calcium> cascade and an acoustic <standing wave> in <water> to route each <photon> toward one of two fixed <polarizers>. Switching took about $10\,\mathrm{ns}$, against $40\,\mathrm{ns}$ for light to cross between stations. <Photomultiplier> <coincidence circuit> rates, with delayed-background subtraction and <polarizer>-removal normalization, violated their <Bell inequality>. Supplementary <polarizers> checked each channel against <Malus's law>. The timing attacked the <locality loophole>, but the authors emphasized that switching was quasiperiodic, not random; incomplete switching and inefficient collection also limited the test. Its normalized statistic differs from the <CHSH inequality> convention used below.<Experimental Test of Bell's Inequalities Using Time-Varying Analyzers by Alain Aspect and others>[pp. 1805-1807, Figs. 2-4; final discussion]{ref}
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