@article{discovery1308370, year = {2005}, volume = {95}, number = {20}, title = {Pre- and post-selection paradoxes and contextuality in quantum mechanics}, month = {November}, journal = {PHYS REV LETT}, note = {{\copyright} 2005 The American Physical Society}, publisher = {AMERICAN PHYSICAL SOC}, issn = {0031-9007}, keywords = {KOCHEN-SPECKER THEOREM, HIDDEN-VARIABLES, ELEMENTS, REALITY}, author = {Leifer, MS and Spekkens, RW}, url = {http://dx.doi.org/10.1103/PhysRevLett.95.200405}, abstract = {Many seemingly paradoxical effects are known in the predictions for outcomes of intermediate measurements made on pre- and post-selected quantum systems. Despite appearances, these effects do not demonstrate the impossibility of a noncontextual hidden variable theory, since an explanation in terms of measurement disturbance is possible. Nonetheless, we show that for every paradoxical effect wherein all the pre- and post-selected probabilities are 0 or 1 and the pre- and post-selected states are nonorthogonal, there is an associated proof of the impossibility of a noncontextual hidden variable theory. This proof is obtained by considering all the measurements involved in the paradoxical effect-the preselection, the post-selection, and the alternative possible intermediate measurements-as alternative possible measurements at a single time.} }