Violation of the Leggett-garg inequality with weak measurements of photons

M. E. Goggin, M. P. Almeida, M. Barbieri, B. P. Lanyon, J. L. O'Brien, A. G. White, G. J. Pryde

Research output: Contribution to journalArticlepeer-review

235 Citations (Scopus)


By weakly measuring the polarization of a photon between two strong polarization measurements, we experimentally investigate the correlation between the appearance of anomalous values in quantum weak measurements and the violation of realism and nonintrusiveness of measurements. A quantitative formulation of the latter concept is expressed in terms of a Leggett-Garg inequality for the outcomes of subsequent measurements of an individual quantum system. We experimentally violate the Leggett-Garg inequality for several measurement strengths. Furthermore, we experimentally demonstrate that there is a one-to-one correlation between achieving strange weak values and violating the Leggett-Garg inequality.

Original languageEnglish
Pages (from-to)1256-1261
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number4
Publication statusPublished - 25 Jan 2011
Externally publishedYes


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