Full Network nonlocality sharing in extended scenario via Optimal Weak Measurements

TL;DR

This paper investigates the sharing of full network nonlocality (FNN) in quantum networks using weak measurements, revealing that active sharing is possible with proper measurements, unlike passive sharing.

Contribution

It introduces the concept of FNN sharing in extended scenarios and distinguishes between passive and active sharing, demonstrating active sharing's feasibility with optimal weak measurements.

Findings

Passive FNN sharing is impossible.

Active FNN sharing can be achieved with proper measurements.

FNN sharing requires more cooperation than Bell or network nonlocal sharing.

Abstract

Quantum networks, which can exceed the framework of standard bell theorem, flourish the investigation of quantum nonlocality further. Recently, a concept of full quantum network nonlocality (FNN) which is stronger than network nonlocality, has been defined and can be witnessed by Kerstjens-Gisin-Tavakoli (KGT) inequalities [Phys. Rev. Lett. 128 (2022)]. In this letter, we explored the recycling of FNN as quantum resources by analyzing the FNN sharing between different combinations of observers. The FNN sharing in extended bilocal scenario via weak measurements has been completely discussed. According to the different motivations of the observer-Charlie1, two types of possible FNN sharing, passive FNN sharing and active FNN sharing, can be investigated by checking the simultaneous violation of KGT inequalities between Alice-Bob-Charlie1 and Alice-Bob- Charlie2. Our results show that passive FNN sharing is impossible while active FNN sharing can be achieved by proper measurements, which indicate that FNN sharing requires more cooperation by the intermediate observers compared with Bell nonlocal sharing and network nonlocal sharing.