Activation of post-quantumness in bipartite generalised EPR scenarios

TL;DR

This paper demonstrates how to activate and detect post-quantum correlations in generalized bipartite EPR scenarios by designing protocols and Bell inequalities that reveal non-quantum behavior.

Contribution

It introduces a protocol for activating post-quantumness in generalized EPR scenarios and derives Bell inequalities that can be violated beyond quantum limits.

Findings

Post-quantum assemblages can generate correlations beyond quantum bounds.

Activation protocols reveal post-quantum nature in generalized EPR setups.

Bell inequalities tailored for these scenarios can witness post-quantumness.

Abstract

In a standard bipartite Einstein-Podolsky-Rosen (EPR) scenario, Alice and Bob share a system prepared in an entangled state and Alice performs local measurements. One possible generalisation of this set-up is to allow Bob to also locally process his subsystem. Then, correlations generated in such generalised EPR scenarios are examples of non-signalling bipartite resources, called assemblages, that can exhibit post-quantum behavior, i.e., cannot be generated using solely quantum systems. There exist assemblages that, despite being post-quantum resources, can only generate quantum correlations in bipartite Bell-type scenarios. Here, we present a protocol for activation of post-quantumness in bipartite generalised EPR scenarios such as the so-called Bob-with-input, measurement-device-independent, and channel EPR scenarios. By designing a protocol that involves distributing the assemblages in a larger network, we derive tailored Bell inequalities which can be violated beyond their quantum bound in this new set-up. Our results show that in all of the above generalised scenarios, the post-quantumness of the assemblages can be witnessed at the level of correlations they produce.