Efficacy of the information causality principle in ruling out beyond-quantum compositions
Phys. Rev. A 112, 022211 – Published 12 August, 2025
DOI: https://doi.org/10.1103/bbnp-6mhv
Abstract
The composition of individual quantum system can mathematically be defined in various ways. However, the no-signaling principle alongside local tomography criteria delineates two possible extreme compositions, commonly referred to as the minimal and maximal compositions. The former (latter) allows for the effects (states) that are beyond-quantum composition. A recent work [Phys. Rev. Lett. 130, 110202 (2023)] demonstrates that the information causality (IC) principle rules out extreme compositions. In this work, we introduce a communication game to show that there are states and effects within both extreme compositions for which the success probability of the game surpasses the maximum achievable quantum bound. However, the IC principle remains satisfied, meaning that it cannot rule out all beyond-quantum correlations resulting from the extreme compositions. This again opens up the question of the effectiveness of the IC principle in ruling out beyond-quantum correlation.
