“All-Versus-Nothing” Contextuality in Graph States

Alexei A. Strakhov, Vladimir I. Man’ko

Bárbara Amaral, Marcelo Terra Cunha

Bárbara Amaral, Marcelo Terra Cunha

Raymond Lal

Samson Abramsky, Rui Soares Barbosa, Giovanni Carù +1 more

An important class of contextuality arguments in quantum foundations are the all-versus-nothing (AvN) proofs, generalizing a construction originally due to Mermin. We present a general formulation of AvN arguments and a complete characterization of all such arguments that arise from stabilizer states. We show that every AvN argument for an n -qubit stabilizer state can be reduced to an AvN proof for a three-qubit state that is local Clifford-equivalent to the tripartite Greenberger–Horne–Zeilinger state. This is achieved through a combinatorial characterization of AvN arguments, the AvN triple theorem, whose proof makes use of the theory of graph states. This result enables the development of a computational method to generate all the AvN arguments in on n -qubit stabilizer states. We also present new insights into the stabilizer formalism and its connections with logic. This article is part of the themed issue ‘Second quantum revolution: foundational questions’.

Boseong Kim, Samson Abramsky

Contextuality is a key feature of quantum information that challenges classical intuitions, providing the basis for constructing explicit proofs of quantum advantage. While a number of evidences of quantum advantage are based on the contextuality argument, the definition of contextuality is different in each research, causing incoherence in the establishment of instant connection between their results. In this report, we review the mathematical structure of sheaf-theoretic contextuality and extend this framework to explain Kochen-Specker type contextuality. We first cover the definitions in contextuality with detailed examples. Then, we state the all-versus-nothing (AvN) argument and define a state-independent AvN class. It is shown that Kochen-Specker type contextuality, or contextuality in a partial closure, can be translated into this framework by the partial closure of observables under the multiplication of commuting measurements. Finally, we compare each case of contextuality in an operator-side view, where the strict hierarchy of contextuality class in a state-side view seems to merge into the state-independent AvN class together with the partial closure formalism. Overall, this report provides a unified interpretation of contextuality by integrating Kochen-Specker type notions into the state-independent AvN argument. The results present novel insights into contextuality, which pave the way for a coherent approach to constructing proofs of quantum advantage.