Is the Interpretation of Delayed-choice Experiments Misleading?

The interpretation of an experimental realization of Wheeler’s delayed-choice gedanken experiment is discussed and called into question. IPNO-DR-07-04 Once more, we find that nature behaves in agreement with the prediction of quantum mechanics even in surprising situations where a tension with relativity seems to appear. It is this quotation from J.S. Bell [1] which brings Vincent Jacques’s report [2] to an end. What is it about? In this ”Experimental realization of Wheeler’s delayed-choice gedanken experiment ” a Mach-Zehnder interferometer is used either in a ”closed” configuration, the usual one, with a phase adjustment leading to the extinction of one photo-multiplicator (PM2), or in an ”open” configuration where the second beam-splitter BS2 has been removed leading to an equal probability for the triggering of PM1 or PM2, as illustrated in the next drawing. single-photon pulse BS1 PM1 (prob.=0.5)