Experimental test of generalized multipartite entropic uncertainty relations

TL;DR

This paper experimentally tests a generalized entropic uncertainty relation in multipartite quantum systems using four-photon entangled states, demonstrating improved bounds and enhanced quantum key distribution security.

Contribution

It provides the first experimental validation of a generalized EUR for multipartite systems, showing improved entropic bounds and practical benefits for quantum cryptography.

Findings

GEUR improves entropic bounds in tripartite systems

Experimental verification using four-photon entangled states

Enhanced secure key rate in quantum key distribution

Abstract

Entropic uncertainty relation (EUR) formulates the restriction of the inherent uncertainty of quantum mechanics from the information-theoretic perspective. A tighter lower bound for uncertainty relations can provide information-theoretic security to quantum communication protocols. Recently, a generalized EUR (GEUR) for the measurement of multiple observables in arbitrary many-body systems has been formulated. Here, we experimentally test this GEUR using a four-photon entangled state with a controllable decoherence channel and show that for the tripartite scenario, the GEUR improves the entropic bound from Renes--Boileau's famous results. As an application, we further demonstrate an improvement of the secure key rate in quantum key distribution from the GEUR. Our results extend the test of EURs into multipartite regimes and may find applications in practical quantum cryptography tasks.