2014/09/30 by Matthew F. Pusey · 2 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physrevlett.113.200401
published as Phys. Rev. Lett. 113, 200401 (2014) · 4 pages. v2: Some typos fixed and some discussions expanded
arxiv created 2014/11/12 · arxiv updated 2014/11/13
The average result of a weak measurement of some observable A can, under post-selection of the measured quantum system, exceed the largest eigenvalue of A. The nature of weak measurements, as well as the presence of post-selection and hence possible contribution of measurement-disturbance, has led to a long-running debate about whether or not this is surprising. Here, it is shown that such "anomalous weak values" are non-classical in a precise sense: a sufficiently weak measurement of one constitutes a proof of contextuality. This clarifies, for example, which features must be present (and in an experiment, verified) to demonstrate an effect with no satisfying classical explanation.