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arXiv · 2307.03489

Every non-signalling channel is common-cause realizable

Paulo J. Cavalcanti·John H. Selby·Ana Belén Sainz
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Abstract

In this work we show that the set of non-signalling resources of a locally-tomographic generalised probabilistic theory (GPT), such as quantum and classical theory, coincides with its set of GPT-common-cause realizable resources, where the common causes come from an associated GPT. From a causal perspective, this result provides a reason for, in the study of resource theories of common-cause processes, taking the non-signalling channels as the resources of the enveloping theory. This answers a critical open question in Ref.~\cite{schmid2020postquantum}. An immediate corollary of our result is that every non-signalling assemblage is realizable in a GPT, answering in the affirmative the question posed in Ref.~\cite{cavalcanti2022post}.

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Paulo J. Cavalcanti, John H. Selby, Ana Belén Sainz. 2025-08-13. Every non-signalling channel is common-cause realizable. https://doi.org/10.1103/physreva.109.042211

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