We formulate stochastic noncontextual hidden-variable theories. In such theories the hidden state \ensuremath{\lambda} specifies not definite values, but expectation values A\ifmmode\bar\else\textasciimacron\fi{}(\ensuremath{\lambda}), . . . of observables A, . . . and noncontextuality means that A\ifmmode\bar\else\textasciimacron\fi{}(\ensuremath{\lambda}) is independent of which other commuting observables commuting with A are measured together with A. We show via Bell inequalities that such theories conflict with quantum theory and propose a two-photon experimental test. We also show that for a single particle of spin ( ${2}^{\mathit{n}}$ -1)/2, quantum violation of classical noncontextuality grows exponentially with n.We formulate stochastic noncontextual hidden-variable theories. In such theories the hidden state \ensuremath{\lambda} specifies not definite values, but expectation values A\ifmmode\bar\else\textasciimacron\fi{}(\ensuremath{\lambda}), . . . of observables A, . . . and noncontextuality means that A\ifmmode\bar\else\textasciimacron\fi{}(\ensuremath{\lambda}) is independent of which other commuting observables commuting with A are measured together with A. We show via Bell inequalities that such theories conflict with quantum theory and propose a two-photon experimental test. We also show that for a single particle of spin (${2}^{\mathit{n}}$-1)/2, quantum violation of classical noncontextuality grows exponentially with n.

Physical Review AOct 1, 199321 citations

Experimental Status of Hidden Variable Theories

S. J. Freedman, Richard A. Holt, Costas D. Papaliolios

Springer eBooksJan 1, 19764 citations

Contextuality in Algebraic Quantum Theory

Yuichiro Kitajima

Klyachko, Can, Binicioğlu, and Shumovsky (KCBS) have introduced an inequality which holds if there is a noncontextual hidden variable theory. It is called KCBS inequality. Its violation shows a contradiction between predictions of quantum theory and noncontextual hidden variable theories. Bell-Kochen-Specker (BKS) theorem also shows that there are no noncontextual hidden variable theories in quantum theory by showing that there is no value assignment on a set of all observables. Thus, its approach is different from KCBS inequality. In the present paper, we show a logical relation between KCBS inequality and a value assignment, and examine a consequence of this logical relation.Klyachko, Can, Binicioğlu, and Shumovsky (KCBS) have introduced an inequality which holds if there is a noncontextual hidden variable theory. It is called KCBS inequality. Its violation shows a contradiction between predictions of quantum theory and noncontextual hidden variable theories. Bell-Kochen-Specker (BKS) theorem also shows that there are no noncontextual hidden variable theories in quantum theory by showing that there is no value assignment on a set of all observables. Thus, its approach is different from KCBS inequality. In the present paper, we show a logical relation between KCBS inequality and a value assignment, and examine a consequence of this logical relation.

Journal of the Japan Association for Philosophy of ScienceJan 1, 20180 citations

Quantum contextuality in the Mermin-Peres square: A hidden-variable perspective

Brian R. La Cour

The question of a hidden variable interpretation of quantum contextuality in the Mermin-Peres square is considered. The Kochen-Specker theorem implies that quantum mechanics may be interpreted as a contextual hidden-variable theory. It is shown that such a hidden-variable description can be viewed as either contextual in the random variables mapping hidden states to observable outcomes or in the probability measure on the hidden state space. The latter view suggests that this apparent contextuality may be interpreted as a simple consequence of measurement disturbance, wherein the initial hidden state is altered through interaction with the measuring device, thereby giving rise to a possibly different final hidden-variable state from which the measurement outcome is obtained. In light of this observation, a less restrictive and, arguably, more reasonable definition of noncontextuality is suggested. To prove that such a description is possible, an explicit and, in this sense, noncontextual hidden-variable model is constructed, which reproduces all quantum theoretic predictions for the Mermin-Peres square. A critical analysis of some recent and proposed experimental tests of contextuality is also provided. Although the discussion is restricted to a four-dimensional Hilbert space, the approach and conclusions are expected to generalize to any Hilbert space.The question of a hidden variable interpretation of quantum contextuality in the Mermin-Peres square is considered. The Kochen-Specker theorem implies that quantum mechanics may be interpreted as a contextual hidden-variable theory. It is shown that such a hidden-variable description can be viewed as either contextual in the random variables mapping hidden states to observable outcomes or in the probability measure on the hidden state space. The latter view suggests that this apparent contextuality may be interpreted as a simple consequence of measurement disturbance, wherein the initial hidden state is altered through interaction with the measuring device, thereby giving rise to a possibly different final hidden-variable state from which the measurement outcome is obtained. In light of this observation, a less restrictive and, arguably, more reasonable definition of noncontextuality is suggested. To prove that such a description is possible, an explicit and, in this sense, noncontextual hidden-variable model is constructed, which reproduces all quantum theoretic predictions for the Mermin-Peres square. A critical analysis of some recent and proposed experimental tests of contextuality is also provided. Although the discussion is restricted to a four-dimensional Hilbert space, the approach and conclusions are expected to generalize to any Hilbert space.

arXiv:2105.00940Physical Review AJan 5, 200923 citations

{2}^{\mathit{n}}

-1)/2, quantum violation of classical noncontextuality grows exponentially with n.