Enriching Diagrams with Algebraic Operations
Alejandro Villoria, Henning Basold, Alfons Laarman
TL;DR
This work develops a framework for enriching diagrammatic reasoning in monoidal categories with algebraic operations by leveraging Eilenberg–Moore algebras for a monad, focusing on affine monads. It proves a free enrichment construction that preserves symmetric monoidal structure and lifts an adjunction to enriched monoidal categories, enabling a semantic bridge to $ extbf{Alg}^T$-enriched ZX-diagrams. The Distribution monad $ extbf{D}$ is used to richly encode probabilistic mixtures, yielding enriched ZX-diagrams whose interpretations are convex combinations of quantum maps, and providing rules to reason about noise in quantum systems. The approach yields a uniform, semantics-driven method to extend ZX-calculus to probabilistic and noisy quantum contexts, with soundness established and completeness left as an open area for future work. Potential impacts include automated reasoning about quantum noise, efficient diagrammatic representations of mixed processes, and extensions to other monads capturing diverse computational effects.
Abstract
In this paper, we extend diagrammatic reasoning in monoidal categories with algebraic operations and equations. We achieve this by considering monoidal categories that are enriched in the category of Eilenberg-Moore algebras for a monad. Under the condition that this monad is monoidal and affine, we construct an adjunction between symmetric monoidal categories and symmetric monoidal categories enriched over algebras for the monad. This allows us to devise an extension, and its semantics, of the ZX-calculus with probabilistic choices by freely enriching over convex algebras, which are the algebras of the finite distribution monad. We show how this construction can be used for diagrammatic reasoning of noise in quantum systems.
