Measurement dependence can enhance security in a quantum network

TL;DR

This paper explores how relaxing measurement independence assumptions in quantum networks can enhance security, demonstrating the creation of stronger nonlocal correlations and implications for secure quantum communication protocols.

Contribution

It introduces a practical framework for understanding measurement dependence effects on network nonlocality and security, including proofs of stronger nonlocality with relaxed measurement independence.

Findings

Relaxing measurement independence can create standard and full network nonlocality.

Full network nonlocality requires all sources to distribute nonlocal resources.

Stronger violations of classical models are achievable with relaxed measurement assumptions.

Abstract

Network Nonlocality is an advanced study of quantum nonlocality that comprises network structure beyond Bell's theorem. The development of quantum networks has the potential to bring a lot of technological applications in sevaral quantum information processing tasks. Here, we are focusing on how the role of the independence of the measurement choices of the end parties in a network works and can be used to enhance the security in a quantum network. In both three-parties two-sources bilocal network and four-parties three-sources star network scenarios, we are able to show, a practical way to understand the relaxation of the assumptions to enhance a real security protocol if someone wants to breach in a network communications. Theoratically, we have proved that by relaxing the independence of the measurement choices of only one end party we can create a Standard Network Nonlocality(SNN) and more stronger Full Network Nonlocality(FNN) and we can get maximum quantum violation by the classical no-signalling local model. We are able to distinguish between two types of network nonlocality in the sense that the FNN is stronger than SNN, i.e., FNN states all the sources in a network need to distribute nonlocal resources.