Advantage of Quantum Theory Over Non-classical Models of Communication

TL;DR

This paper introduces a communication task where quantum resources enable perfect success, demonstrating a unique advantage of quantum theory over other non-classical models with supra-quantum correlations.

Contribution

The paper proposes a novel authentication task that quantum resources can solve perfectly, unlike classical or other non-classical theories, highlighting quantum advantage in communication.

Findings

Quantum resources achieve perfect success in the proposed task.

Classical and some non-classical theories cannot guarantee perfect success.

The task demonstrates a unique quantum advantage over all known non-classical strategies.

Abstract

Quantum correlations provide dramatic advantage over the corresponding classical resources in several communication tasks. However a broad class of probabilistic theories exists that attributes greater success than quantum theory in many of these tasks by allowing supra-quantum correlations in `space-like' and/or `time-like' paradigms. In this letter we propose a communication task involving three spatially separated parties where one party (verifier) aims to verify whether the bit strings possessed by the other two parties (terminals) are equal or not. We call this task {\it authentication with limited communication}, the restrictions on communication being: (i) the terminals cannot communicate with each other, but (ii) each of them can communicate with the verifier through single use of channels with limited capacity. Manifestly, classical resources are not sufficient for perfect success of this task. Moreover, it is also not possible to perform this task with certainty in several non-classical theories although they might possess stronger `space-like' and/or `time-like' correlations. Surprisingly quantum resources can achieve the perfect winning strategy. The proposed task thus stands apart from all previously known communication tasks as it exhibits quantum advantage over other non-classical strategies.