Full Network Nonlocality Based Security In Quantum Key Distribution

TL;DR

This paper demonstrates how full network nonlocality can enhance the security of quantum key distribution protocols, outperforming traditional Bell nonlocality-based methods by reducing quantum bit error rates.

Contribution

It introduces a four-partite network-based QKD protocol utilizing full network nonlocality and compares its security advantages over Bell-CHSH based protocols.

Findings

Full network nonlocality improves security over Bell nonlocality.

Quantum bit error rate can be reduced below 13.7% using full network nonlocality.

The proposed protocol is more secure than Bell-CHSH based QKD.

Abstract

In the last decade research of quantum nonlocality has moved beyond the regime of standard Bell nonlocality to consider network-based experimental set-ups involving multiple independent sources. Notion of full network nonlocality has emerged as some truly network phenomena that cannot be realized in traditional Bell experiments. Present work manifests utility of such form of truly network non-classicality in designing a four partite network-based entanglement assisted quantum key distribution protocol. To be more precise, security of the protocol relies upon full network nonlocality detection via violation of some suitable trilocal inequality. Based on the quantum bit error rate and violation of trilocal inequality, arbitrary two qubit entangled states are characterized in accordance with their utility in successfully executing the protocol. Intuitively, owing to connected structure of entangled sources, any genuine form of network nonlocality may offer advantage over standard Bell nonlocality for designing secure key distribution protocols. To establish that as a fact, another QKD protocol relying upon Bell-CHSH nonlocality detection in all pairs of sender and a receiver party is designed. The former turns out to be more secure compared to the latter. Importantly, while the quantum bit error rate can be less than 14.6% exploiting Bell-CHSH nonlocality, it can be reduced below 13.7% by exploiting full network nonlocality.