Information Causality without concatenation

TL;DR

This paper introduces a new approach to applying the principle of Information Causality to Bell inequalities, replacing concatenation with channel capacity limits, simplifying derivations and extending applicability.

Contribution

It demonstrates that replacing concatenation with channel capacity limits simplifies derivations and extends the application of Information Causality to more Bell scenarios.

Findings

Replaces concatenation with capacity limits in Information Causality

Simplifies derivations of nonlocality bounds

Extends bounds to new Bell scenarios

Abstract

Information Causality is a physical principle which states that the amount of randomly accessible data over a classical communication channel cannot exceed its capacity, even if the sender and the receiver have access to a source of nonlocal correlations. This principle can be used to bound the nonlocality of quantum mechanics without resorting to its full formalism, with a notable example of reproducing the Tsirelson's bound of the Clauser-Horne-Shimony-Holt inequality. Despite being promising, the latter result found little generalization to other Bell inequalities because of the limitations imposed by the process of concatenation, in which several nonsignaling resources are put together to produce tighter bounds. In this work, we show that concatenation can be successfully replaced by limits on the communication channel capacity. It allows us to re-derive and, in some cases, significantly improve all the previously known results in a simpler manner and apply the Information Causality principle to previously unapproachable Bell scenarios.