double slit

The double-slit experiment is used as thearchetypal interference experiment to dramat-ically demonstrate the quantum weirdness ofwave-particle duality. It is a long-held assump-tion that whether which-way detectors are placedat one slit or both will yield the same results, ren-dering the second detector redundant. Here weshow that the presence of the second detector canhave measurable effects on the interference pat-te, violating this assumption. We show thatthis effect forms the basis for a new measure ofBo rule violation which is correct to all orders.It opens new experimental opportunities for theaccurate testing of the Bo rule.Particle nature is demonstrated in double-slit experi-ments by placing which-way detectors at the slits. Thereason that a second which-way detector is believed to beredundant, is that a detection at one slit means that theparticle is assumed to not have gone through the otherslit. Now on the other hand, in the Feynman path inte-gral formulation of quant