The geometry of simplicial distributions on suspension scenarios

TL;DR

This paper explores the topological and geometric structure of simplicial distributions in quantum measurement scenarios, revealing how suspension constructions relate to contextuality and Bell inequalities.

Contribution

It introduces a topological framework using cone and suspension constructions to analyze the geometry of simplicial distributions and contextuality in quantum measurements.

Findings

The cone construction transforms measurement spaces into joins of polytopes.

Suspension measurement spaces can be decomposed to understand contextuality.

New Bell inequalities are derived from the geometric analysis.

Abstract

Quantum measurements often exhibit non-classical features, such as contextuality, which generalizes Bell's non-locality and serves as a resource in various quantum computation models. Existing frameworks have rigorously captured these phenomena, and recently, simplicial distributions have been introduced to deepen this understanding. The geometrical structure of simplicial distributions can be seen as a resource for applications in quantum information theory. In this work, we use topological foundations to study this geometrical structure, leveraging the fact that, in this simplicial framework, measurements and outcomes are represented as spaces. This allows us to depict contextuality as a topological phenomenon. We show that applying the cone construction to the measurement space makes the corresponding non-signaling polytope equal to the join of $m$ copies of the original polytope, where $m$ is the number of possible outcomes per measurement. Then we glue two copies of cone measurement spaces to obtain a suspension measurement space. The decomposition done for simplicial distributions on a cone measurement space provides deeper insights into the geometry of simplicial distributions on a suspension measurement space and aids in characterizing the contextuality there. Additionally, we apply these results to derive a new type of Bell inequalities (inequalities that determine the set of local joint probabilities/non-contextual simplicial distributions) and to offer a mathematical explanation for certain contextual vertices from the literature.