2001/04/11 by Yakir Aharonov, Alonso Botero, Sandu Popescu +2 · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1016/s0375-9601(02)00986-6
7 pages, 1 figure
arxiv created 2001/04/11 · arxiv updated 2015/06/26
Classical-realistic analysis of entangled systems have lead to retrodiction paradoxes, which ordinarily have been dismissed on the grounds of counter-factuality. Instead, we claim that such paradoxes point to a deeper logical structure inherent to quantum mechanics, which is naturally described in the language of weak values, and which is accessible experimentally via weak measurements. Using as an illustration, a gedanken-experiment due to Hardy\citehardy, we show that there is in fact an exact numerical coincidence between a) a pair of classically contradictory assertions about the locations of an electron and a positron, and b) the results of weak measurements of their location. The internal consistency of these results is due to the novel way by which quantum mechanics "resolves" the paradox: first, by allowing for two distinguishable manifestations of how the electron and positron can be at the same location: either as single particles or as a pair; and secondly, by allowing these properties to take either sign. In particular, we discuss the experimental meaning of a \em negative number of electron-positron pairs.