Principle of information causality rationalizes quantum composition

TL;DR

This paper demonstrates that the principle of information causality can be used to derive the structural features of multipartite quantum systems, ruling out certain non-quantum compositions based on information-theoretic constraints.

Contribution

It provides a new information-theoretic rationale for the structure of quantum state and effect spaces in multipartite systems, extending the principle of information causality.

Findings

Maximal tensor product composition permits non-quantum states.

Minimal tensor product composition allows only separable, Bell local states.

Neither composition aligns with the principle of information causality.

Abstract

Principle of information causality, proposed as a generalization of no signaling principle, has efficiently been applied to outcast beyond quantum correlations as unphysical. In this letter we show that this principle when utilized properly can provide physical rationale towards structural derivation of multipartite quantum systems. In accordance with no signaling condition state and effect spaces of a composite system can allow different possible mathematical descriptions even when description for the individual systems are assumed to be quantum. While in one extreme, namely the maximal tensor product composition, the state space becomes quite exotic and permits composite states that are not allowed in quantum theory, the other extreme -- minimal tensor product composition -- contains only separable states and the resulting theory allows only Bell local correlation. As we show, none of these compositions does commensurate with information causality, and hence get invalidated to be the bona-fide description of nature. Information causality, therefore, promises information theoretic derivation of self-duality of state and effect cones for composite quantum systems.